6 inch Nylon Rigid Wide Trolley Caster Wheels | Taiwantrade.com
CMCO - BUDGIT RIGID MOUNT PUSH-TYPE TROLLEY; 905402 | eBay
Amazon.com: AUEAR, 4 Pack 1 Inch Rubber Caster Wheels Heavy Duty Fixed Casters with Rigid Non-Swivel Base Trolley Wheels Top Plate 1 Inch Diameter : Industrial & Scientific
Budgit Rigid Mount Push Trolley - for Wider Beams - Paducah Rigging