These bearing cover guide rollers feature a V-groove surface and a single bearing. They are optimal for medium load applications, used for sliding doors or carrier transport. These rollers can be used with commercial polished hexagonal steel bar for rails. Hardened steel rollers provide water resistance and prevent damage from intrusion of ships and other debris. Body is made from heat-treated 4135 steel with a black oxide finish. Bearing and C-type retaining ring are made from steel.