Amazon.com: GBL Heavy Duty Retractable Workbench Caster Wheels + Screws - Set of 4 Castor Wheels up to 500Lbs - No Floor Marks Castors for Portable Furniture or Work Bench : Industrial & Scientific
Amazon.com: DOZAWA Workbench Stepdown Caster, Set of 4 Durable Heavy Duty Steel Retractable Caster Wheels, All Steel Construction Urethane Wheels [New Version] (700LBS) : Industrial & Scientific