A free-standing medical service column has front and rear chases with service outlets mounted on at least the front side for connection with fluid and electrical conduits. The column includes vertically extending tracks at each corner, which tracks extend substantially the height of the column. Brackets, holders, and equipment are connected to the tracks by means of locking slide assemblies. Each slide assembly includes a base and a slide element formed of a low-friction material. A screw interconnects the base with the slide element such that rotation of the screw moves the slide toward the base and against the wall of the channel to frictionally secure the slide within the channel. Members secured to the column by means of locking slide elements may also carry a bracket. The bracket includes a plug formed of resilient material, which plug is received in a cylindrical bore of the member. When the bracket is rotated to a desired position of adjustment, the plug is expanded radially outwardly into frictional engagement with a wall of the bore to affix the bracket immovably to the member. The chases are formed entirely of non-flammable material to eliminate the need for enclosing the electrical lines within metal conduits.