Industrial Sliding Four Wheel Door Roller. M12 X 60mm Fixing -Cowdroy OM51300 | Elraco Distributors.
Amazon.com: Prime-Line N 7533 Sliding Closet Door Roller Kit, 3/4 In. Wheel Diameter, Convex (Round) Edge Plastic, Stamped Steel Construction, Includes 3/8 and 1/2 In. Offset Pairs (2 Pack) : Tools & Home Improvement
Aluminium Alloy Heavy Duty Sliding Roller Track With ESD Black Wheel