The 5ive Star Gear GI Spec LC-II ALICE Packs are made to the same specs as the original US military version with a rugged and durable nylon material. These backpacks are part of the U.S. military's system of all-purpose, lightweight individual carrying equipment that has been the American standard since the 60's. The medium size can be worn alone or with the ALICE pack frame, but the large size can only be worn with the frame. Item is compatible with the 5ive Star Gear GI Spec LC-II ALICE Pack Frame.