Safety Wheels: These wheels are suitable for storage racks with a bolt-free self-locking shelving system, for easy movement and secure display.,Heavy Duty Bearings: 500 lbs maximum total capacity, locking wheel with ball bearing, durable steel construction, high strength, corrosion-resistant.,Easy to Use: With these wheels installed, your rack can roll easily and no longer needs to stand still, runs quietly and absorbs shock and vibration, bring a max loading capacity and safety, installs on your existing storage rack.,Premium and Durable: Wheel material is PU (Polyurethane), 3 inch size, 4 Pack caster wheels.