Features： 1、Made of full CNC precision machining aluminum alloy, anti-slip. 2、Easy to install and remove, convenient for you to use. 3、With this seat post tube adapter, you can change the bicycle seat tube to the size you want. 4、Suitable for MTB bike, mountain bike, road bike, etc. 5、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. Specification： Features: Made of full CNC precision machining aluminum alloy, anti-slip,  light weight and durable. Easy to install and remove, convenient for you to use. With this seat post tube adapter, you can change the bicycle seat tube to the size you want. Suitable for MTB bike, mountain bike, road bike, etc. 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. 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 28.6mm 60mm/2.36inch 13g 27.2mm to 30mm 60mm/2.36inch 22g 27.2mm to 30.4mm 60mm/2.36inch 29g 27.2mm to 30.8mm 60mm/2.36inch 25g 27.2mm to 31.6mm 60mm/2.36inch 37g 27.2mm to 33.9mm 60mm/2.36inch 54g Package list: 1 * Bike Seatpost Tube Adapter Package List：