MOLLE was developed by the U.S. Army Natick Soldier Research, Development and Engineering Center as an updated backpack system for soldiers. Though the MOLLE system has grown to include different aspects of load carrying, the original research emphasized a new rucksack to replace the All-purpose, Lightweight, Individual Carrying Equipment (ALICE). Key improvements in the MOLLE backpack included a more comfortable design, with a lighter, more durable, plastic frame that better contoured to the wearer's back. The adjustable torso height also allowed manufacturers to make a single, one-size-fits-all bag, instead of the two different sizes made in the ALICE style.
The MOLLE program included other improvements to how equipment was carried and used. These modifications include a new vest called the Fighting Load Carrier (FLC) and modular pouches that could be added and removed. This was a direct replacement of the Load Bearing Vest (LBE). MOLLE also accommodated a tube-fed drinking water system. Finally, both of these systems, the MOLLE bag and the FLC, included a modular attachment system called PALS.
PALS is a series of nylon strips that are stitched at consistent intervals, to create a series of rugged loops. These strips are often placed in rows all across bags and vests, to allow users to attach compatible systems at any place. Manufacturers can then custom-design pouches that are PALS compatible, and users with PALS-integrated equipment can attach those pockets in whatever fashion suits them.
PALS is used as part of the MOLLE system. PALS serves as a straightforward loop design, developed by Natick Labs. As Hans Halberstadt says in his book, "Battle Rattle," MOLLE is "really a living system that is constantly being refined." PALS has been an important part of the evolution of MOLLE but has not, itself, been significantly changed. Though pouches designed for MOLLE are technically PALS-compatible, they are often sold as "MOLLE -compatible." MOLLE seems to be the term more often associated with any aspect of the equipment carrying system which includes the PALS loops, from backpacks to armor-plated vests.