referring now to the figures , wherein like reference numerals represent like parts throughout the several views , exemplary embodiments of the present disclosure will be described in detail . throughout this description , various components may be identified having specific values , these values are provided as exemplary embodiments and should not be limiting of various concepts of the present invention as many comparable sizes and / or values may be implemented . referring to fig2 - 11 , there are shown various perspectives of an embodiment of a side wall and cover system 100 of the present invention that form a containment system . the side wall and cover system 100 as shown is installed onto a slide - n - roll conveyor slider bed 102 ( hereinafter , “ slide - n - roll bed ”), manufactured by asgco ®. however , a person of ordinary skill in the art would appreciate that the side wall and cover system 100 could be installed onto other apparatuses that provide a troughing configuration for the carry side 11 a of a conveyor belt 11 , including , but not limited to , impact cradle beds , roller cassette conveyor belt impact beds and sliders , slide - lers ™ ( such as those made , e . g ., by asgco ®), and the like . as shown in fig2 , the slide - n - roll bed 102 includes support members 104 , which are longitudinally spaced from each other and are secured to the belt support frame ( not shown ). a horizontally oriented conveyor roller 108 is centrally positioned on each support member 104 . on either side of each conveyor roller 108 , resilient impact bars 110 are secured to and extend across the support members 104 on angled wings 112 , running lengthwise in what would be the conveyor belt travel direction . the impact bars 110 are oriented at an angle on either side of each conveyor roller 108 to create a troughing angle for the carry side 11 a of the conveyor belt 11 . by way of example only , these angled wings 112 comprise an angle of approximately 35 °, although various wing configurations could be used in the range of 20 °- 45 °. through use , impact bars 110 and rollers 108 can become worn and in need of replacement . to replace or service the impact bars 110 or rollers 108 , it is preferred that the wings 112 are releasable and outwardly slideable along the length of the support member 104 , so as to render these components accessible for servicing or replacement . the side wall and cover system 100 shown in fig2 - 11 , includes a lid or cover 114 affixed to vertical walls 216 on either side thereof . the walls 216 are secured to the wings 112 of the slide - n - roll bed 102 . the cover 114 is preferably made of a light material capable of maintaining structural integrity under its own weight , such as aluminum . in the embodiment shown , the cover 114 is gable - shaped , e . g ., at an angle of 20 °, although other angles and shapes ( e . g ., rounded ) are contemplated . the exact shape of the cover 114 is less important than the fact that it allows for clearance of materials being transported on the belt 11 below . thus , a portion of the wall 216 slides under wings 112 and is fastened via top bar bolts , as is discussed in more detail below . referring to fig8 a , 9 and 10 , each wall 216 includes a preferably vertical wall portion 218 , a preferably horizontal inwardly projecting ridge 220 ( fig1 ) extending from the top of the wall portion 218 and flat projection 224 extending inwardly at a downward angle from the bottom of the wall portion 218 ( as used “ inwardly ” refers to a direction towards the center of the slide - n - roll bed 102 .). the angle of the flat projection 224 conforms to the angle of the angled wing 112 . this side wall configuration , i . e ., the vertical wall portion 218 with the horizontal inwardly projecting ridge 220 , provides additional conveying volume at the sides of the conveyor , as can be mostly clearly seen from fig8 a . on either side of the cover 114 is a flat lip 124 ( fig2 ). the lip 124 of the cover 114 is adapted to rest above the ridge 220 of the wall 216 . preferably , a gasket 126 ( fig2 ) is positioned between the ridge 220 and the lip 124 . the lip 124 of the cover 114 is secured to the gasket 126 and ridge 220 , thereby securing the cover 114 to the wall 216 via hand knobs , bolts or other fasteners 117 ( fig2 and 11 ) that may be inserted through holes 128 , 130 and 132 respectively ( see fig2 ) located in the lip 124 , gasket 126 and ridge 220 . thus , the lid 114 is attached to walls 116 via hand knobs 117 and the wall 116 is flanged outward . as can be most clearly seen in fig1 , corresponding cinch nuts 117 a are press fitted into the ridge holes 132 for receiving the hand knobs 117 therein . the projection 224 preferably slides under an upper / outer portion of each wing 112 to enable securing the wall 216 to each wing 112 . to secure the projection 224 to each wing 112 , bolts or other fasteners located in the back side of the uppermost impact bar 110 are used to pass through apertures in the angled wing 112 and the projection 224 . in particular , top bolts or other fasteners 111 ( fig2 b ) have their heads trapped within a channel 113 on the back side of the uppermost impact bar 110 . when the uppermost impact bar 110 is brought into the vicinity of the angled wing 112 , the shank of the fastener 111 is inserted through the slot 136 of the angled wing and through the aperture 134 in the projection 224 ( fig4 a ). the slot 136 allows for adjustment during this securing process . a nut can be secured to the shank of the fastener 111 ( fig2 b ) to lock the components together . preferably , rubber pads 140 are positioned on the upper side of each projection 224 and adjacent to each wing 112 so as to provide a seal between the wall 216 and each wing 112 . the rubber seal 140 is secured ( e . g ., adhesively secured ) to the projection 224 and overlaps a section of the belt 11 so as to prevent dust and particulate from escaping the confines of the side wall / cover system 100 and spreading over the side and underneath the belt 11 . an inside seal element 230 ( fig1 ) is secured to the flat projection 222 of wall 216 also to prevent dust and particulate from escaping the confines of the side wall / cover system 100 and spreading over the side and underneath the belt 11 . this inside seal element 230 comprises a rubber material and is secured to the projection 222 using wedge clamps 232 that secure a seal bar 233 ( e . g ., an aluminum panel ) and the inside seal element 230 to the projection 222 . as shown most clearly in fig2 , the seal bar 233 prevents the wedge clamps 232 from distorting the upper edge of the inside seal element 230 as the wedge clamps 232 are tightened against the projection 222 . the cover 114 preferably includes an interlock tab 142 ( fig2 - 2a ) positioned respectively on near and / or far edges thereof ( as used herein , “ near edge ” of the cover 114 refers to a first edge under which the belt 11 runs while “ far edge ” of the cover 114 refers to a second edge under which the belt 11 runs ). it is contemplated that the cover 114 can be part of a modular set , i . e ., adapted to mate with and create a seal between other cover sections over a determined length of the belt 11 . modular compatibility of covers with one another is advantageous in that it allows a user to remove only a single cover from a plurality of covers when necessary , e . g ., to gain access to the area directly below a specific cover . the interlock tab 142 is adapted to secure each cover to an adjacent cover . furthermore , in order to permit a series of side wall / cover systems 100 to be releasably coupled together , each side wall 216 comprises fore and aft flanges 234 a / 234 b that project outwardly from the wall . see fig1 . these flanges 234 a / 234 b are preferably welded to the vertical wall portion 218 . the fore flange 234 a comprises a pair of vertically - oriented holes while the aft flange 234 b comprises a pair of vertically - oriented slots . a second side / cover system 100 can be located in front of and behind another system 100 as shown in fig1 . the slots in the aft flange 234 b of a first side wall / cover system 100 allow a bolt ( not shown ) to be adjustable which then passes through a corresponding hole in the fore flange 234 a of the adjacent side wall / cover system 100 . removing or replacing a roller 108 can be time consuming and inconvenient . accordingly , there is shown in fig1 - 12c , a center roll hanger 400 that may be used to retain a roller 108 , e . g ., in the slide - n - roll bed 102 . the advantage of this embodiment of the center roll hanger 400 is that it does not require a user to remove a sidewall and cover system 100 to remove or replace a roller 108 therefrom / thereto . the center roll hanger 400 includes flanges 402 , each of which has a horizontally - oriented notch 404 adapted to receive a hexagonal roller protrusion 406 , which extends outwardly from each side of the roller 108 . the horizontal - orientation of the notch 404 enables the roller to be inserted in and removed from the center roll hanger 400 in a horizontal direction . the 404 preferably includes a slight vertical indent 408 ( e . g ., ¼ of an inch deep , as shown in fig1 c ) adapted to mate with the hexagonal roller protrusion 406 . the roller 108 may be secured via a clip attachable to the side of each flange 402 . this configuration of the center roll hanger 400 avoids the need to lift the belt 11 much , if at all , and enables a user to remove / replace the roller without having to remove the sidewall and cover system 100 . it should be understood that while a hexagonal mating configuration between the notch 404 and roller protrusion 406 is preferred , other interlocking geometric configurations are contemplated , including , but not limited to , square , triangular , rectangular , trapezoidal , pentagonal , heptagonal , octagonal , interlocking teeth or bumps , and the like . accordingly , in one aspect , the present invention comprises a novel sidewall and cover system 100 . in another aspect , the present invention includes a novel center roll hanger 400 having flanges 402 , each of which comprises a horizontally - oriented notch 404 . this configuration permits the removal and replacement of rollers from a slide - n - roll bed 102 or the like , that avoids the need to remove a sidewall and cover system 100 , if such system is secured to a slide - n - roll bed 102 ( or the like ). thus , the center roll hanger 400 allows the roller 108 to be removed / replaced without having to slide out a wing 112 and center slide assembly . while the invention has been described in detail and with reference to specific examples thereof , it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof .