This Heavy Duty Lazy Susan Swivels is constructed of corrosion-resistant galvanized steel. Ball bearings are set in deep race groove allowing for resistance free movement, strength, and stability. Ball bearings can be greased as required. Mounting screws not included.Properties SPECIFICATIONS: Size: 3 inch Shape: Square Ball Bearings: 1/4 inch Nominal Balanced Load Capacity: 200 Lbs Suggested Turntable Diameter: up to 18 inch Size: 4 inch Shape: Square Ball Bearings: 1/4 inch Nominal Balanced Load Capacity: 300 Lbs Suggested Turntable Diameter: up to 12 to 25 inch Size: 6 inch Shape: Square Ball Bearings: 1/4 inch Nominal Balanced Load Capacity: 500 Lbs Suggested Turntable Diameter: up to 15 to 30 inch Size: 12 inch Shape: Square Ball Bearings: 1/4 inch Nominal Balanced Load Capacity: 1000 Lbs Suggested Turntable Diameter: < 20 inch