The Little Joe Seatpost Seal from Syntace is a simple 20mm seal that you place on your seatpost to stop grit from entering the frame, ruining either your frame, seatpost or both. It is made from BASF Polyurethane which has the perfect sealing properties as it is open pored & densely foamed with a very tough elastic & is abrasion resistant. Available in 3 different diameter sizes depending on your frame or fork tube size.