Feature: 1. NICE PERFORMANCE: Made of high quality aluminum alloy material with high strength and wear resistance, having good performance for long service life, make every outdoor travel more comfortable. 2.FINE WORKMANSHIP: Has received CNC milling, fine polishing and anodizing workmanships to form a high strength replacement, providing a satisfying using experience, bringing a pleasant and relaxing experience. 3.WIDELY USE: Equipped with 11 teeth, suitable for 8, 9, 10, 11 speed rear derailleur, can replace the old or damaged part with better performance. 4.SUIT FOR: Suitable for guide roller and tension wheel, installation shaft diameter is compatible with the range of 4, 5 and 6mm, there are fewer restrictions and barriers during use. 5.SPECIAL DESIGN: Adopts a new structure of clamp spring which is smooth for riding, making you feel ease and convenient during use. Specification: Item Type: Bicycle Rear Derailleur Pulley Material: Aluminum Alloy + Ceramics Application: for Road Bike, Mountain Bike Inner Diameter: 6mm/0.2in Weight: Approx.10g/0.4oz Package List: 1 x Guide Wheel 2 x Reduction Sleeve