The mountainx 31 backpack is set up for the biggest mountain bike excursions and adventures made from highly durable waterproof pu coated nylon with a roll top to keep your contents dry one of the best features of this bag is the removable inner compartment sheets which allows you to separate two sections inside the bag so you can keep clean and dirty kit apartcomfort in use is sorted out by a well padded back carrying system with built in ventilation channels and an additional padded waist