There are two carbon steel ball bearings inside the pulley, which can reduce the friction of the wheel. The pulley rotates more flexibly and has no noise. Made of stainless steel, anti-rust, corrosion-resistant, outdoor use can also prevent corrosion of the pulley. Compared with other pulleys, the pulley wheel support plate is thicker, the wheels are stronger, and the bearing capacity is stronger. The pulleys are detachable for easy installation. A single small pulley can bear 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: 16mm (0.629in) Groove depth: 7mm (0.27in) Product weight: 840g (1.851lb) Load: 300kg (660 Ib) Application Usually used as a rail wheel Track wheel Package Contents: 3pcs x U-type Pulley Only the above package content, other products are not included. Note: Light shooting 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.