The canteen is intended primarily for use in temperate and tropical environments for carrying drinking water.
The field pack is used to carry individual rations and equipment that are essential during field operations. It is designed to permit certain items to be carried in a number of different ways to meet changing conditions. For example, the poncho, can be carried inside the pack under the expandable flap or it can be attached to the bottom of the pack by means of the two adjustable securing straps. Extra items of small clothing, such as underwear and socks, also can be rolled and placed under the expandable flap. Outer clothing not in use can be secured under the pack or under the flap, depending on the location of the poncho. In placing items in the field pack, hard objects such as ration cans should be placed on the outside, with softer items such as clothing on the inside toward the wearer's back. A series of eyelets at the edge of the pack flap will accommodate the double hooks used on old field equipment carriers for such items as wire cutters and machetes.
Military specification MIL-C-43103 covers one type of plastic water canteen having a capacity of one quart nominal.
Military specification MIL-F-40165 covers one type and size field pack fabricated from olive drab cotton duck and webbing.