The Problem Solvers Seatpost Shim is what you need when your seatpost is a little too small-diameter to fit tightly into your frame. It's made of light and durable aluminum and has a lip on the top so it won't slide down inside the frame during installation.
|3.2mm shim, 27.2 seatpost to 30.4 frame||708752011526||ST0232||ST0232|
|1.2mm shim, 25.4 seatpost to 26.6 frame||708752024359||ST0512||ST0512|
|3.2mm shim, 25.4 seatpost to 28.6 frame||708752024397||ST0532||ST0532|