General description Used as an electric door top wheel, this M12 48 x 50 mm PP Steel Roller Bearing Guide Wheel is versatile and can serve as a placement door nylon flange wheel, iron door wheel, electric door wheel guide, track wheel, and pulley. Made of durable PP steel, it features two 6201ZZ bearings, making it a great replacement for old or damaged bearings. Technical specifications Dimensions: 48 x 50 mm Material: PP steel Bearing type: 6201ZZ