The Alice buttpack technique is 3 - 4 different models from M56, M61, M73 (Technical name for the Alice system), and M88 buttpacks.
M88 Buttpacks are nylon M56 buttpacks but with plastic or metal D rings instead of eyelets on fabric tabs.
Materials and sizing have changed over time leading to an immense variety and alot of choice to adding addition storage and carrying capacity to your kit.
Buttpacks stopped being issued with the M73 Alice system leading to many older types being used instead, the IIFS system created the ICBP being the last buttpack ever issued for any of the Alice gear, being fully nylon and replacing all of the tri glides and buckles with plastic it is specifically made to fit the IIFS vest but can be attached onto Y harness and Pistol belt. (Though this is not recommended)
