according to an illustrative example , a gas spring is provided within a base tube of a chair column . the piston rod of the gas spring is axially supported on a bottom of the base tube . the cylinder of the gas spring is axially and rotatably guided within a guide at the upper end of the base tube . the guide comprises a main sleeve body and a guiding sleeve body inserted into a central passage of the main sleeve body . these sleeves are provided on their surfaces facing each other with at least one projection , and / or at least one recess which engage each other in a snap fit .