Size:13T Material type:Aluminum Batteries included?:No Product Dimensions:8 x 8 x 5 cm; 19.92 Grams Features: - Adopting aluminum alloy and ceramic material, this product is very durable to use. - Can be applied for most mountain bike. - Supporting for various speed shifting. - Suitable for use 4 / 5 / 6 mm guide wheel screws. - Offers you a better cycling experience. Specifications: Item: Bike Guide Roller Material: Aluminum Alloy + Ceramic Colour: Black, Golden (Optional) Diameter: 4 cm / 1.6 inch (11 T), 5 cm / 2.0 inch (13 T) Weight: 21-23 g Package Included: 2 * Bike Guide Roller 2 * Installation Hole Adapter Tubes (Other things on the pictures are not included) About this item [Material]: Made of high quality aluminum alloy material, the bike rear pulley is lightweight and durable [High Quality]: Anti rust and corrosion material ensure long time use and resistant anodized machined bicycle jockey wheel ensure normal working [Easy to Install]: Package contains 1 pair of bike jockey wheels, and there are 2 installation hole adapter tubes which help you install easily [Various Speed]: Our product fits for most mountain bike of 11T or 13T, suitable for use 4 / 5 / 6 mm guide wheel screws [100% Satisfaction]: If you have any question about this item, please feel free to contact us, we will help you within 24 hours on week days [Material]: Made of high quality aluminum alloy material, the bike rear pulley is lightweight and durable [High Quality]: Anti rust and corrosion material ensure long time use and resistant anodized machined bicycle jockey wheel ensure normal working [Easy to Install]: Package contains 1 pair of bike jockey wheels, and there are 2 installation hole adapter tubes which help you install easily [Various Speed]: Our product fits for most mountain bike of 11T or 13T, suitable for use 4 / 5 / 6 mm guide wheel screws [100% Satisfaction]: If you have any question about this item, please feel free to contact us, we will help you within 24 hours on week days