Gio Seatpost 27.2 to 31.6mm Shim Go to amazon.com Related posts Expert choice for seatpost shim 31.6 Feature27.2 Inner diameter, 31.6 outer diameter - will convert a 27.2 seat post to fit a 31.6 seat tube.Length: 100mmMaterial : AlloyWeight : 52 g DescriptionSeat post Shim Converter 27.2 post to 31.6 tube 52 grams.Will convert a 27.2 seat post to fit a 31.6 seat tube.