The ortlieb seat post bag the large lightweight and waterproof ortlieb saddlebag 4l is an easy way to carry plenty of spares and tools its integrated tool free system makes switching the pack between bike extremely quick and simple the waterproof pu coated nylon and cordura is well sealed with a roll closure supported further with a pair of elastic straps making sure the pack is tightly secured every ride whatever yoursquore carrying this is the larger version of the s