Leg Extension Seat Post 5" for 22.2mm plus shim for 25.4mm Extend your legs 5" back compared to a straight seat post 22.2mm seat post plus shim to convert to 25.4mm 22.2mm is standard size for 16" and 20" bicycle frames With the shim the seat post can be used with most 26" cruisers Note: 22.2mm is 7/8", shim is 1/8", with the shim on post is 1"