Description: Anodized CNC machined bicycle jockey wheel with fully rubber sealed bearing for center bolt derailleurs. It run on smooth ball bearings, and it's a necessary accessory for your bicycle. There are three different colors for you to choose from, to meet different needs.;Fits for;most of rear derailleur on the market, support 7/8/9/10 speed.;Hope you will enjoy your cycling. Have a nice day. Features: 1. Made of CNC aluminum alloy, lightweight and durable. 2. Anti rust and corrosion resistant anodized. 3. These pulleys run on smooth ball bearings. 4. A necessary accessory for your bicycle. 5. Apply for most of rear derailleur on the market, support 7/8/9/10 speed. Specifications: Material: 7005 Aluminium Alloy Components:;Derailleurs Structure:;Ceramic Bearings Color: Red, Blue, Silver (optional) Size: 11T, 13T (optional) Use: For 7/8/9/10 speed Diameter: 11T-40mm, 13T-50mm Quantity: 2pcs Package Weight: approx. 20g-11T, 23g-13T Fit For: For 4/5/6mm;roller screw axis Package Included: 2 x;Ceramic Bearings Note: 1.;Please allow 1-3mm error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing; slightly different from the real object. Please in kind prevail.