Prime-Line Products 1901 Round Tub Enclosure Roller, 7/8-Inch, 2-Pack 7/8 inch outside diameter This product is manufactured in china Tub enclosure sliding shower door roller Ball bearing with threaded Hex hub Threaded hex hub 7/8in. nylon ball bearing oval wheel (2) wheels with screws Fits most V shaped tracks 7/8 In. tall