The Back Pack has a capacity of 6 US gallons (22 litres) and is 24"h x 20"w (61cm x 51cm) when empty. Manufactured from a strong polyester based fabric, protected by a thermoplastic polymer. It has a 4" filling port with a removable debris screen, 3" wide fully padded shoulder straps. Weighs approximately 50lbs. (22.7kg) when full.