Yundxi 2pcs Bicycle Rear Derailleur Pulley, 10T/11T/12T/13T/14T/15T/16T/17T Aluminum Alloy Jockey Wheel Ceramic Guide Pulley Bike Guide Roller Wheel for 4/5mm Guide Wheel (15T,Black)

• Lightweight & Durable: Made of quality aluminum alloy with fully sealed bearing for center bolt derailleurs, Durable to use and longer life Ceramic Bearing Pulley: New upgrade design, with ceramic bearing, can reduce the resistance during cycling, which ensures fast and sensitive working. Improve riding efficiency. Smooth Ride: Deep toothed guide wheel to reduce chain drop. Positive and negative tooth guide wheel can effectively inhibit the horizontal swing of the chain, so that the speed is more accurate. Installation: These derailleur pulley set are very easy to install with an allen key by simply removing the screw that holds the pulley to the derailleur. Includes accessory for compatibility with 4mm and 5mm screw thickness. Do not over-tighten because it would increase friction with the rear derailleur reducing the bike jockey wheel performance Compatible Design: Our Bike Rear Derailleur Pulley is more compatible, it fits almost all mountain bikes and road bikes, and fit 4/5mm screws.