Three Rucksacks in one! The Rocket Pack can be used when fully zipped together using all available 70 liters/ 4270 cu.in. It can also be used as a smaller 40 liter/2440 cu.in. rucksack, by unzipping the two detachable side pockets (rockets) at the side of the pack. However if a smaller day pack is needed, by zipping the rockets together using the small additional yoke harness (available as an optional extra), a smaller 30 liter/1830 cu.in rucksack can be made. Zip on detachable side pockets are compatible with army issue yoke. All harnesses and back system are air mesh padded for extra comfort when carrying. Special Features : 40 liter /2440 cu.in. Center compartment plus 2 x 15 liters /915 cu.in. detachable pockets = 70 liters / 4270 cu. in , Outer lid pocket and Inner lid pocket, 2 mesh storage side pockets, Under pack pocket w/ waterproof nylon cover desert, Adjustable chest strap, Adjustable waist strap, Contoured shoulder harness, Adjustable Internal Frame