High-performance ball bearings: Made of PP/polyurethane and steel, very sturdy and durable. 30?kg (66?lbs) per caster, 2?inch (40?mm) diameter ball transfer units. Smooth and quiet: The precision ball bearing in the antique roller clockwork movement is pleasantly smooth. The 2;; furniture casters protect hardwood, laminate, tile, slate and all other low pile carpets or other non-sensitive floors. WIDE APPLICATION: These casters are ideal for small sofas, chairs, stools, benches, TV stands, microwave carts and plant stands, shoe bins, toy bins and other small furniture. Specifications: Main Material: Polyurethane/Plastic, Metal. Shaft Diameter: 5/16; x 1 1/2; (8mm x 38mm) Wheel Diameter: 2; x 2; / 50mm x 50mm (D x D). Mounting Height: 2.4;/60?mm. Load Capacity (Single): 30?kg maximum Total Height (including 5? long stem): 85?mm. Weight: 810 gr. Package Includes: 4 sets of office chair casters. Application: These mainly chair casters are ideal for office chairs, dining room chairs, game