For 6 years and hundreds of miles I humped ALICE and ALICE II packs with 23rd Marines. They can be very uncomfortable compared to a civilian pack but they will carry a very heavy load and take a hell of a beating. They carry the load away from your back and high, this helps with cooling but it makes you "rear heavy" with a heavy load. Make sure the frame including the rivets are in good shape. The pack, belt, and straps can all be switched or repaired but the frame must be in good shape. I like the ALICE II. It is larger with 3 additional small pockets. Just the right size for a pair of socks, important for a grunt. Remember they are unpadded so you need to wrap everything. I still have one.