Prime-Line Products M 6003 Tub Enclosure Flat Roller, 7/8-Inch,(Pack of 2) Two No. 8-32 x 3/8" Phillips binder head machine screws Threaded hex hub Made in China Threaded hex hub 7/8in. nylon ball bearing flat wheel (2) wheels with screws Fits most J shaped tracks 7/8 in. tall