The U.S. military uses smoke hand grenades as “a ground-to-ground or ground-to-air signaling device, target or landing zone marking devices, or screening devices for unit movements,” according to the Grenades and Pyrotechnic Signals Field Manual FM 23-30. The M-18 grenade uses several colors of smoke.
The body of the M-18 grenade is composed of a sheet steel cylinder with four emission holes that allow the smoke to escape when the grenade is ignited. The filler contains 11.5 oz. of colored smoke mixture that may be red, yellow, green or violet. An M201A1 is used to ignite the grenade, which weighs 19 oz.
Operation of the M-18 grenade must be used in a sequence of steps. First, remove the tape from the grenade bottom to expose the filler, then remove the fuse by unscrewing it from the grenade. Ignite the starter mixture with a naked flame, then throw the grenade immediately to avoid burn injury.
The smoke mixture is ignited by the flame, and the grenade will release a cloud of colored smoke for approximately 50 to 90 seconds. Beware of using the M-18 grenade in dry areas due to risk of fire.