These bearing cover guide rollers feature a V-groove surface and double bearings. They are optimal for heavy-duty load applications, used for sliding doors or carrier transport. These rollers can be used with commercial polished hexagonal steel bar. Hardened steel rollers provide water resistance and prevent damage from intrusion of ships and other debris. Body is made from nickel-plated 1045 steel, heat-treated 4135 steel with a black oxide finish, or 303 stainless steel. Bearing and C-type retaining ring are made from steel or stainless.