Please check product compatibility carefully to ensure it is the product you need So as not to waste your time and energy on return. Main Characteristics: WHEEL MATERIALS AND PERFORMANCE: Heavy duty casters made of polyurethane wheels. Premium Caster wheels are made of high quality polyurethane wheels with strong abrasion resistance, silent shock absorber, wearproof, no drag marks and enhance the impact resistance of the whole caster. Quantity – 4 Castor Wheels per Set Material – Polyurethane Loading Capacity – 100 kg per Castor (Still Loading Capacity 800 kg per set) Precision Double Ball Bearing on Each Wheel Ball Bearing on Swivel Top .