it is expressly emphasized with reference to the following description that the invention is not limited to the exemplary embodiments and , for that matter , to all or several features of the described feature combinations . rather , each individual partial feature of the / each exemplary embodiment can have inventive significance also per se , separately from all other partial features described in connection therewith , and also in combination with any features of another exemplary embodiment as well as independently of the feature combinations and back - references of the claims . first , a preferred embodiment of a connection device 1 will be described in more detail with reference to fig1 and 2 . this connection device 1 provides a fast and preferably also releasable connection of a media line 2 by simply inserting a line end into a receiving opening 4 of a connecting element 6 . the insertion direction is shown with an arrow x in fig1 . since there is no connecting pin for attachment of the media line 2 , it can also be called a “ pinless plug - in system .” specific inner parts 5 ( see fig2 ), which interact with the media line 2 in particular for axial guidance , mechanical locking to prevent unintentional release , peripheral sealing , and , if required , inner radial support , and preferably also for an intentional release process , are mounted inside the receiving opening 4 of the connecting element 6 . a retaining element , which is configured as a spring elastic toothed ring 8 with an outer peripheral area 8 a and with several retaining teeth 8 b distributed over the periphery , extending radially inward and inclined transversally in the insertion direction x and thus configured with friction and / or positive locking in the manner of a barbed hook against the outer peripheral surface of the media line 2 , is mounted within the receiving opening 4 in order to lock the inserted media line 2 to prevent withdrawal . at least one peripheral seal 10 , which seals an annular gap relative to the outside radially between the media line 2 and the connecting element 6 , is additionally mounted within the connecting element 6 in order to seal the inserted media line 2 relative to the outside . the peripheral seal 10 is thus located radially directly between the media line 2 and the connecting element 6 and thus completely seals the connecting element 6 relative to the outside as single media seal . the outer peripheral area 8 a of the toothed ring 8 rests in undeformed state in a vertical plane with respect to the longitudinal axis y of the connection device 1 , while the retaining teeth 8 b rest jointly on a cone as a result of their inclined position . the retaining teeth 8 b in undeformed state define with their inner retaining edges a perimeter whose diameter is smaller than the outer diameter of the media line 2 . as a result , the retaining edges exert a radial retaining force especially with positive locking or at least friction locking against the outer periphery of the inserted media line 2 . the toothed ring 8 is mounted with its outer peripheral area 8 a with a defined limited radial movement play within the connecting element 6 . this axial movement play is limited by means of bilateral axially opposite contact sections 12 and 14 within the connecting element 6 . a first contact section 12 is formed on the “ lower ” side ( fig1 ) when viewed in the insertion direction x by means of a radial contact surface that is transverse to the longitudinal axis y and a second contact section 14 is arranged on the axially opposite “ upper ” side in the radial outward area of the toothed ring 8 . the contact sections 12 and 14 are axially separated from each other by an open space that is greater than the axially measured thickness of the peripheral area 8 a of the toothed ring 8 . from the difference “ distance of contact sections 12 , 14 minus thickness of the peripheral area 8 a of the toothed ring 8 ,” the axial movement or play of the toothed ring 8 is obtained . further , the toothed ring 8 interacts — see also fig5 in this regard — at the angular transition 15 between the outer peripheral area 8 a and the retaining teeth 8 b with a peripheral tilting edge 16 provided within the connecting element 6 on the radial inner periphery of the radial contact surface that forms the first contact section 12 , such that when the media line 2 is inserted , due to the media line contact with the retaining teeth 8 b , the toothed ring 8 is pivoted or twisted like a rocker about the tilting edge 16 out of a starting position in which it presses with its outer peripheral area 8 a against the first “ lower ” contact section 12 until the outer peripheral area 8 a arrives on the radial outer side for supported contact on the second , axially opposite “ upper ” contact section 14 . the outer radial periphery of the peripheral area 8 a of the toothed ring 8 that is pivoted like a rocker around the tilting edge 16 , consequently lifts from the first contact section 12 and is moved against the second contact section 14 . starting from this position , an elastic flexural deformation still occurs basically only in the area of the retaining teeth 8 b , which radially surmount the tilting edge 16 on the inside if the media line 2 is moved further in the insertion direction x . the insertion process is then concluded in that the media line 2 is retracted a little counter to the insertion direction x . thus the retaining teeth 8 b act with positive locking or at least friction locking on the outer periphery of line 2 . in addition , a support sleeve 20 is preferable coaxially arranged within the receiving opening 4 of the connecting element 6 in such a way that the media line 2 can be pushed toward a cylindrical outer surface 22 of the support sleeve 20 during insertion , wherein the support sleeve 20 or its cylindrical outer surface 22 has an outer diameter da that is adapted to the inner diameter di of the media line 2 in such a way that the inserted line 2 is radially supported by the support sleeve 20 , and deformations of the media line 2 within the operating range of the toothed ring 8 from a radial retaining force produced by the toothed ring 8 are prevented . it can preferably be provided herein that the support sleeve 20 has a support section 23 with greater inner wall thickness within the operating range of the toothed ring 8 . the support sleeve 20 has a cylindrical plug - in section 24 that fits into an inner socket 26 of the connecting element 6 for the purpose of retaining the support sleeve 20 inside the connecting element 6 . a stop 28 for the line 2 also functions as an insertion limit for the support sleeve 20 . another advantageous embodiment of the connection device 1 provides that the connection element 6 has a housing that is axially divided in two , with a first nozzle - like housing part 30 , which is directed in the insertion direction , and a second sleeve - like housing part 32 , which forms an outlet side of the receiving opening 4 . the first housing part 30 can be designed as desired , for example , as a distributor with a different number of outlets , a straight through - connector ( fig1 ) as well as an angular connector or as an l - shaped , t - shaped or y - shaped connector . the two housing parts 30 , 32 are preferably connected to each other via a peripherally closed snap - on connection 34 ; see in particular fig1 . in the presented preferred embodiment , for this purpose the first housing part 30 axially and radially engages , in a form fitting manner , an inner notch - like locking recess 38 of the second housing part 32 with a plug - in section 36 ; see fig2 . the first housing part 30 can be configured as a screw - in socket with an outer thread attachment 40 . the above - described tilting edge 16 for the toothed ring 8 is advantageously formed on an insert ring 42 , which also has the first contact section 12 in the form of an end face that is axially outwardly adjacent to the tilting edge 16 and vertical to the longitudinal axis y . the tilting edge 16 is thus formed at the transition between the end face that forms the first contact section 12 and an adjacent cone surface 44 ; see also fig5 . it is further provided herein that the insert ring 42 delimits a sealing chamber 50 for the peripheral seal 10 in axial direction within the connecting element 6 with an end face 46 pointing in the insertion direction together with a flank face 48 of the connecting element 6 lying axially opposite thereto or of the first housing part 30 . the first housing part 30 is advantageously configured without undercuts on the inside in the insertion direction x . this means that the inner diameter can only be greater in the direction opposite to the insertion direction x , but cannot be smaller at any point . the inner parts 5 , namely the peripheral seal 10 , the insert ring 42 , and the toothed ring 8 can as a consequence be mounted by means of a simple axial insertion . in addition , the peripheral seal 10 need neither be radially expanded nor radially compressed . the above second upper contact section 14 for the outer peripheral area 8 a of the toothed ring 8 is likewise preferably formed on a ring - shaped insert element 52 , which is supported within the connecting element 6 according to fig1 , and in particular within the second housing part 32 , in the pipe release direction . the second contact section 14 is formed herein by an end face at the end side of an axially projecting annular web 54 of the insert element 52 , wherein this annular web 54 preferably also engages the first housing part 30 or in its plug - in section 36 . for releasability of the inserted media line 2 , which is locked by the toothed ring 8 , it is advantageous to provide a sleeve - like release element 56 . this release element 56 engages the connecting element 6 in an axially displaceable manner in such a way that the toothed ring can be elastically deformed by being pushed by the release element 56 in the insertion direction x so that the line 2 in the region of the retaining teeth 8 b is released . for this purpose , the release element 56 works with an actuation section 58 against the retaining teeth 8 b . the release element 56 prevents unintentional release of the media line 2 when a force k is exerted on the media line 2 , which the force k is directed transversely to the longitudinal axis y of the connection device or when a force is directed one - sided on the release element 56 . for this purpose the release element 56 on the media line 2 and on the sleeve - shaped housing part 32 as well as the media line 2 on the release element 56 and the cylindrical outer surface 22 of the support sleeve 20 is guided in such a way — see arrows f 1 to f 4 in fig1 — that tipping of the release element 56 and thus release of the media line 2 are prevented ; see fig1 . the release element 56 is preferably held within the connecting element 6 by a catch mechanism 60 to prevent disassembly ; see also fig4 . for this purpose , at the end pointing in the insertion direction x , the release element 56 is provided with locking arms 62 ( fig2 ) that with radially outwardly pointing notches engage a radial stepped surface 64 ( see fig1 ) within the connecting element 6 . this stepped surface 64 is advantageously formed on the insert element 52 ( see also fig3 and 4 ). in another advantageous embodiment , the locking arms 62 can be connected to the remaining peripherally closed ring part of the release element 56 by means of hinge - like constrictions 66 , whereby the radial mobility of the locking arms 62 is improved . furthermore , the release element 56 has on the one hand an outer peripheral seal 68 and on the other hand an inner peripheral seal 70 . the outer peripheral seal 68 serves to seal an annular gap between the sleeve - like release element 56 and the connecting element 6 or its second housing part 32 . the inner peripheral seal 70 seals an annular gap in the direction of the line 2 . in addition , in a preferred embodiment the outer peripheral seal 68 also functions as a spring element to generate an axial resetting force for the release element 56 . finally , in the represented preferred modification of the connection device 1 , an annular , cover - like closure element 72 is also provided for closing an annular partial opening on the outlet side of the receiving opening 4 , which encloses the inserted media line 2 . according to fig1 , this closure element 72 also seals the area of the inner peripheral seal 70 . in this way the inner peripheral seal 70 can be inserted in the release element 56 in a simplified manner , since no undercut is present in this area of the release element 56 . steam jet protection is also provided by means of the closure element 72 . in addition , the closure element 72 can also have at least one axially outwardly projecting attachment , not shown , as a lever for manual actuation of the release element 56 . a novel building system is now provided according to the invention for producing the connection device 1 , wherein a design for different cross - sectional dimensions of the media line 2 is possible with the always identical connecting element 6 . optionally different inner parts 5 , which are always identical with regard to the inner contour of the receiving opening 4 , can be used for this purpose according to the invention in the connecting elements 6 designed for a specific maximum outer line diameter d max — see fig4 in this regard — to fit at least two different media lines , which differ in cross - sectional dimensions . the inner parts 5 can each be adapted for this purpose , on the one hand to the always identical inner contour of the receiving opening 4 of the connecting element 6 , and on the other hand to the cross - sectional dimension of one of the different media lines 2 . in an advantageous embodiment , one and the same connecting element 6 can be adapted by means of different inner parts 5 to at least three and in particular six different media lines 2 , which differ in cross - sectional dimensions . as regards the toothed ring 8 — see in particular the enlarged representation in fig5 in this regard — it is configured in its different modifications , adapted to different media lines 2 , and especially to different outer diameters d of lines , with peripheral areas 8 a with different radial widths , such that the retaining teeth 8 b define different diameters with their inner radial tooth edges to fit the specific outer line diameters d with proportions that remain otherwise identical with regard to teeth length and angular alignment . this means that from a practical point of view the retaining teeth 8 b “ wander ” only in the radial direction through the outer peripheral areas 8 a , differing in width , of the different toothed rings 8 . this is easy to understand using the representation in fig5 ; the possible range of dimensions is shown there with a double arrow 74 . this allows adaptation of the toothed ring 8 for an area of the outer line diameter d between a specific maximum diameter d . and a specific minimum diameter d min according to fig3 , in particular in several steps , through at least three different toothed rings 8 . since the change of the outer line diameter d also changes the peripheral length , an adjustment of the quantity of retaining teeth 8 b and / or their peripheral width and / or the peripheral width of the tooth gaps must also take place in modifications of the specific adapted toothed ring 8 in order to achieve identical proportions of the retaining teeth 8 b with regard to angular inclination , length , and thus deformation behavior . further , as regards the peripheral seal 10 — see in particular fig3 and 5 in this regard — it is configured in several embodiments that are fitted to different outer line diameters d , where these embodiments provide differently dimensioned ring cross sections and inner diameters respectively adapted to different outer line diameters d where the outer diameter of the peripheral seal 10 is always the same . a peripheral seal 10 is shown in a solid line in fig3 and 5 with a smaller annular cross section for a design for the largest outer line diameter d max , while a design of the peripheral seal 10 for the smaller outer line diameter d min is represented with broken lines . any desired subdivisions are also possible here . furthermore , different release elements 56 must be made available for the different line cross sections . it is provided for this purpose that the release element 56 define different inner diameters adapted to the respective outer line diameters d in different modifications , with the outer contour remaining unchanged . the end actuation section 58 , pointing in the insertion direction , is always in the radial position in the area of the retaining teeth 8 b of the corresponding toothed ring 8 . further , the locking arms 62 of the release element 56 always have identical spring properties , with constant deformation length and identical articulated areas in their different modifications . the radial measured width 1 of the locking arms 62 in the area of the above constrictions 66 is in particular always constant for that purpose in all modifications . this is shown in fig4 by means of double arrows 76 and by means of the reference letter 1 . the release force can likewise remain constant as a result of the variation in quantity of locking arms 62 in different line sections . this is also advantageously achieved in combination with the spring properties by means of the constant radial width 1 of the locking arms 62 . the above outer peripheral seal 68 of the release element 56 for sealing the annular gap in the direction of the connecting element 6 is identical in all modifications . the inner peripheral seal 70 indeed has accordingly different inner diameters with preferably identical ring cross section ( the same “ cord thickness ”) in the different modifications adapted to the different outer line diameters d . an inner contact area 70 a of the release element 56 for the inner peripheral seal 70 can be accordingly modified ; see fig3 in this regard . other important adjustments are carried out in the area of the insert ring 42 ; see fig5 in this regard . the result is that the insertion ring 42 is configured , on the one hand , on the side of the toothed ring 8 to fit its different modifications with end faces of different radial width in different modifications , so that the tilting edge 16 is always in the transition 15 at the start of the retaining teeth 8 b . the above cone surface 44 likewise “ wanders ” only in the radial direction with the same length and angular inclination . on the other hand , the insertion ring 42 is also configured with different length in the axial direction ; this is to fit different peripheral seals 10 for any required so - called “ groove filling ” ( degree of filling of the sealing chamber 50 ) for optimal seal compression by accordingly varying the axial width of the sealing chamber 50 ; see the double arrow 78 in fig5 in this regard . in addition , the end face 46 of the insert ring 42 , which axially delimits the sealing chamber 50 , is adjusted in radial width to the outer line diameter d in such a way ( see the double arrow 80 ) that a radial gap between the media line 2 and the annular area having the end face 46 is dimensioned so small that the peripheral seal 10 cannot possibly be pressed under media pressure into the gap between the line 2 and the insert ring 42 ( minimization of a so - called gap extrusion ). a further adjustment takes place in the area of the closure element 72 , in that the latter is adjusted to the respective media line 2 with regard to its inner diameter in its different modifications . reference is made in particular to fig3 and 4 in this regard . as for the support sleeve 20 , it must be especially adjusted to the respective inner line diameter di in the area between a largest inner diameter di max and a smallest inner diameter di min ; see fig3 and 4 in this regard . the cylindrical outer surface 22 with a corresponding outer diameter “ da ” is configured for this purpose ; see fig1 and 2 . the insert section 24 provided for retention as well as preferably also the stop 28 are identical in all modifications , however ; see in particular fig6 . the previous description suggests that the following inner parts 5 are used in adapted modifications in the always identical connecting elements 6 for adjustment to different outer line diameters d : peripheral seal 10 , insert ring 42 , and toothed ring 8 , as well as release element 56 with peripheral seals 68 , 70 and the closure element 72 . adjustment to the inner line diameter di can also take place — also alternatively — by using an adapted modification of the support sleeve 20 . the insert element 52 is identical within a “ cluster ” in all modifications and belongs therefore in fact to the inner contour of the receiving opening 4 of the connecting element 6 . it is further noted that the measurements entered in fig4 and 5 and respectively identified with the same upper case reference letters are also respectively interpreted in the same way in the differently dimensioned inner parts 5 . finally it should be remarked in a general way that only two different designs of the inner parts 5 are illustrated in the representations of fig3 to 6 . they are the two extremes , although other intermediate designs are possible . thus the connecting element 6 , for example , can be designed with an inner contour for a maximum outer line diameter d max of 10 mm . lines 2 with an outer diameter of 9 mm , 8 mm as well as optionally intermediate sizes of , for example , ⅜ ″ can be connected by means of different inner parts 5 . lines with different wall thicknesses s , for example , 1 mm , 1 . 5 mm , 1 . 25 mm , can be assembled herein by means of the corresponding support sleeves 20 ; see the measurements s 1 and s 2 plotted for this purpose in fig4 . any other intermediate sizes as well as any desired designs for other groups of differing media lines 2 with any desired intermediate sizes are naturally also possible . the invention also allows adjustment to more than six media lines 2 , different in cross - sectional length , within the “ cluster ” group . equal or at least very similar properties with regard to the mechanical support of the line 2 and behavior during release of the line 2 as well as with regard to the sealing properties can be advantageously achieved by means of the aforementioned measures within a / each “ cluster ” group with the same connecting element 6 , that is , the same housing parts 30 , 32 , for several different media lines 2 , which differ in cross - sectional dimensions , specifically the outer and / or inner diameter . a sealing system with at least approximately the same degree of filling and the same seal compression is created for sealing by means of the following features : constant outer diameter of the peripheral seal 10 functioning as single media seal for application within a sealing area of the connecting element 6 with constant inner diameter ; always identical flank surface 48 in the connecting element 6 in the direction of the lower axial limit of the sealing chamber 50 ; different ring cross sections ( cord thicknesses ) of the peripheral seal 10 for adaptation of the inner seal diameter to the outer line diameter ; differing radial width of the end faces 46 of the insert ring 42 for upper axial limitation of the sealing chamber 50 and prevention or at least minimization of a so - called gap extrusion of the peripheral seal 10 ; different axial lengths of the insert ring 42 for optimal seal compression over the end face 46 ; always identical outer peripheral seal 68 functioning as dirt seal ; always identical ring cross section ( cord thickness ) of the inner peripheral seal 70 functioning as dirt seal with differently adjusted ring diameters ( inner and outer diameter ); and varying inner diameter of the contact area 70 a for the inner peripheral seal 70 within the release element 56 . the following features are of importance for the constant mechanical properties : always the same angular alignment of the retaining teeth 8 b of the toothed ring 8 ; and always the same free “ lever ” length of the retaining teeth 8 b . the invention is not restricted to the exemplary embodiments illustrated and described , but also includes all modifications acting in the same manner within the meaning of the invention . it is expressly emphasized that the exemplary embodiments are not restricted the combination of features , but that individual partial feature has inventive importance per se also separately from all other partial features . furthermore , the invention is also not limited to the feature combination defined in the respective independent claim , but can also be defined by any other desired combination of specific features of all individual features disclosed as a whole . this means that in principle virtually any individual feature of the respective independent claim can be omitted or replaced by at least one individual feature disclosed at another point in the application . to this extent , the claims are to be understood as merely a first formulation attempt for an invention .