The ortlieb seatpost bag 15l versatile and lightweight one simple tool free manoeuvre is all it takes to fix or remove the waterproof seatpost bag made of pu coated nylon and cordurareg the integrated mounting allows quick change from bike to bike the roll closure with elastics ensures safe closing of the bag and allows tight packing ortlieb seatpost bag 15l features individually adjustable ratchet closure compatible with seat post diameters from 254 mm t