The Unify Padded Combo Seat has a one-piece plastic core which forms the seat and post. This padded seat is now available in the new slim version, and the molding is re-inforced so you will be able to knock a few extra ounces off your bike. *100% nylon with inner 6061-T6 alloy centre post, kevlar or canvas topcover. *25.4mm seat post *Seat combo designed for riders running low seats .