Permits Showcase Doors to Move Smoothly and Quietly This CRL Showcase Track Roller is a nylon wheel designed to work with the DV146 Aluminum H-Bar Shoe and DV149 Aluminum Bottom Track. Minimum Order: 1 Each This Nylon Roller Assembly slips into the cut end of the H-Bar Shoe and is held in place when the two screws in the wheel housing are tightened.