This is a Kenna Track Mfg. pocket door roller. It measures 3 3/4" x 7/8" with wheels. SWISCO made a similar reproduction but has ceased production of this roller. You can read about it on their website, www.swisco.com. This Kenna Track Mfg. roller originally came with brass or rubber wheels. We may make reproductions with plastic wheels. Wheels alone are available if needed.