Specification: Material: Aluminum Alloy Color: black Options: 27.2mm to 28.6mm, 27.2mm to 30mm, 27.2mm to 30.4mm, 27.2mm to 30.8mm, 27.2mm to 31.6mm, 27.2mm to 33.9mm Size/Length/Weight:27.2mm to 28.6mm60mm/2.36inch13g27.2mm to 30mm60mm/2.36inch22g27.2mm to 30.4mm60mm/2.36inch29g27.2mm to 30.8mm60mm/2.36inch25g27.2mm to 31.6mm60mm/2.36inch37g27.2mm to 33.9mm60mm/2.36inch54g Package list: 1 * Bike Seatpost Tube Adapter Aluminum Alloy Material: The bike tube adapter is made of full CNC precision machining aluminum alloy material, aopts anti-slip design. Easy to Install: The bike seatpost is easy to install, it does not need some complicated tools and convenient for you to use. We also provide detailed installation instructions to help you complete the installation. Modified Size: With this seat post tube adapter, you can change the bicycle seat tube to the size you want. So as to achieve a more comfortable riding Wide Applications: The aluminum alloy bicycle seatpost tube adapter is suitable for MTB bike, mountain bike, road bike, etc. Note: This seatpost tube adapter has six different sizes, please check the outer diameter of your bicycle seat tube. Measure the inner diameter of the old clamp. Or measure the outside diameter of the seat tube. Then make the right choice.