The ultimate adventure pack, the Impetro Gear Modular Backpack features a single base unit with 4 zip-on pack options; hike, bike ski, and mountain. The base unit features an innovative X-harness, water bladder compartment, ergonomic back shape and padding, height adjustable waist belt, and a few zippered pockets to keep the essentials. From smallest to largest, the Hike pack features a 10L capacity, a softlined pocket, and dual water bottle pockets for those shorter days on the trails. The Bike pack features a 15L capacity, goggle pocket, tool and pump pocket, knee pad holder, and a rain cover for longer rides. The Ski pack features a 22L capacity, goggle pocket, ski and snowboard carry options, shovel and probe compartment, and a helmet net for your next ski tour. Finally, the Mountain pack features a 33L capacity, a top flap closure with storage, external webbing, multiple zippered pockets and gear holders, and a rain cover for your next big objective day!