The battle bag, or Mann bag, is a lightweight load carrying system designed to allow the combat infantryman to carry enough ammunition and ancillaries such as medical supplies, spare batteries, and radio equipment. There are a multitude of different suppliers for these, with the British Army having designed its own version for issue under the PECOC programme. The key compartments, or pouches, on the battle bag consist of the main compartment, 3 to 4 ammo pouches, an FFD (trauma dressing) pouch, and a radio pouch, which is usually mounted within the main compartment. Some designs of battle bags have MOLLE strips on them, to allow the user to accessorise the bag to their operational requirements. Others, such as the BlackHawk bag, have an internal map case.
The battle bag was originally designed for use as a "grab bag", to allow drivers and vehicle-borne troops to grab essential supplies in a dismount for such functions as an ambush or the assault phase of a mechanised attack. From there, it has spread in popularity with troops due to its ability to be worn comfortably over body armour, as well as the fact that it can be rapidly removed from the wearer in a medical emergency, or to allow the wearer to crawl through "mouseholes" (small jagged holes blown through compound walls with explosive charges).