Description: Made of anodized CNC aluminum alloy and upgraded bearing, lightweight and durable. Machined bicycle jockey wheel with fully sealed bearing for center bolt derailleurs. Apply for most rear derailleur of 13 teeth in the market. A rear derailleur needs 2 pulley wheels. Necessary accessories for your bicycle. Specification: Material: aluminium alloy Pulley Wheel Size(Diameter): approx. 5cm/1.97inch Bolts Size(Diameter): 0.4cm/0.16inch, 0.5cm/0.2inch Color: red, black, gold, blue Package Includes: 1 Piece 13 Teeth Bike Pulley Wheel 2 Pieces Bolts(4mm and 5mm)