BNVB Alloy Bike Seatpost Shim, 100mm Length Aluminum Bicycle Reducing Sleeve Seat Post Tube Adapter, Diameter Switch 25.4-27.2mm; 27.2-28.6/30.0/30.4/30.9/31.6mm; 30.9-31.6mm. (31.6mm to 34.9mm)

Length: 100mm, Guarantee you seatpost insert safe., Material: Made of high quality 6061 aluminum alloy, CNC machining CD texture surface, Light weight, anti-rust and durable., Easy Install: Easy to install and remove, Convenient for you to Switch Seatpost in need., Suit for MTB bike, mountain bike, road bike etc., Note: Please measure the outside diameter of your seatpost, (or check the size marks on the seatpost). Then measure your bike frame seat tube inside diameter. Then choose right Size.