There are two carbon steel ball bearings inside the pulley, which can reduce the friction of the wheel. The pulley turns more flexibly and has no noise. Stainless steel manufacturing, rust - proof, - , outdoor use can also prevent pulley . Compared with other pulleys, pulley wheel support plate is thicker, the wheels are stronger and the bearing capacity is stronger. Pulleys are removable for easy installation. A single small pulley can carry 660lb/300kg Specification Product Name: U Type Pulley Color: Silver Material: 304 stainless steel Installation height: 54mm(2.125in) Wheel diameter: 48mm(1.889in) Wheel thickness: 22mm(0.866in) Groove width: 16 mm(0.629in) Groove depth: 7 mm(0.27in) Product weight: 280g(0.617lb) Load: 300 kg (660 Ib) Application Generally used as a rail wheel Grooved Wheel Package Contents: 1pcs * U-Type Pulley Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.