Borroughs 4" Caster Kit for Workbenches (Pack of 4)
POWERTEC New Workbench Caster Kit (4-Pack) 17001 - The Home Depot
Amazon.com: POWERTEC 17002 Workbench Caster Kit with Quick-Release Plates and Polyurethane Wheels, 400 LB Total Weight Capacity - Set of 4 : Industrial & Scientific