Prime-Line Products 1901-B Flat Tub Enclosure Roller, 3/4-Inch, 2-Pack, 3/4" D X 3/8" W, White 3/4" Outside Diameter This product is manufactured in China Tub Enclosure Sliding Shower Door Roller Ball Bearing With Threaded Hex Hub Threaded hex hub 3/4in. nylon ball bearing flat edge wheel 2 wheels with screws Fits most J shaped tracks 3/4 in. tall Threaded hex hub 3/4in. nylon ball bearing flat edge wheel 2 wheels with screws Fits most J shaped tracks 3/4 in. tall