PREMIUM MATERIALThe bicycle ceramic pulley is made of CNC aluminum alloy, lightweight and durable. ANTI RUST AND CORROSION CRAFTSMANSHIPAnti rust and corrosion, durable anodized machined , ensures long-term use, the bicycle pulley ensures normal operation. 7 or 8 or 9 or 10 SPEED SUPPORT The bicycle rear derailleur pulley applies to most derailleurs market rear, support 7 or 8 or 9 or 10 speed. A must-have accessory for your bike. PERFECT PERFORMANCE The bearing wheel pulley is applied with full rubber sealed bearing for center bolt derailleurs which protect the bike. These pulleys run on smooth ball bearings. WARRANTYIf you are not satisfied with our product you received, you can email us at any time. We will get back to you instantly and help you solve your problem. Product Description Anodized CNC machined bicycle jockey wheel with full rubber bearing for center bolt derailleurs. It runs on smooth ball bearings, and it's a must-have accessory for your bike. There are three different colors to choose from, to meet different needs. Suitable for most rear derailleurs in the market, support 7 or 8 or 9 or 10 speed. Hope you enjoy your cycling. Have a nice day. Features: 1. PREMIUM MATERIALThe bicycle ceramic pulley is made of CNC aluminum alloy, lightweight and durable. 2. ANTI RUST AND CORROSION CRAFT Anti rust and corrosion, durable anodized machined, ensures long-term use, the bicycle pulley wheel ensures normal operation. Specifications: Material : 7005 aluminum alloy Components: Derailleurs Structure: ceramic bearings Color: red Size: 11T, 13T (optional) Usage: For 7 or 8 or 9 or 10 speed Diameter: 11T-40mm, 13T-50mm Quantity: 2 pieces Package weight: approx. 20g-11T, 23g-13T Suitable for: For 4 or 5 or 6mm Roller Screw Axle Package Included: 2 x Aluminum Bearings ceramic Note: 1. Please allow 1-3mm error due to manual measurement. Thank you 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.