Bike seatpost shim sleeve, inner diameter is 27.2mm/1.07inch, 4 types of outer diameter to choose.use this seatpost sleeve adapter ring, you can use 28.6mm/30.0mm/30.4mm/31.6mm seatpost on your 27.2mm bike seatpost.
Bike seatpost adapter, can be converted to 27.2 seatpost diameter of 30.4 or 30.8 or 31.6 diameter.
Seatpost adapter shim suit for MTB bike, mountain bike, road bike etc.
Bike seatpost shim, before buy, please check your bike frame seat tube outside diameter. measure the inside diameter of your old clamp.Or measure the outside diameter of your seat tube (on your bike frame).