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, durable aluminum and has a lip on the top so it won't slide down inside the frame during installation.
|2.8mm shim, 27.2 seatpost to 30.0 frame||708752011502||ST0228||210000014852|
|3.7mm shim, 27.2 seatpost to 30.9 frame||708752012851||ST0237||210000032988|
|0.7mm shim, 30.9 seatpost to 31.6 frame||708752077386||ST0250||210000051194|