The M18A1 Claymore mine is essentially a shaped C-4 plastic explosive charge that fires a swarm of metal ball bearings in a predetermined direction. It is detonated by a firing trigger that is wired into the mine; multiple mines can be linked in a chain to a single trigger. It can also be linked to a tripwire-style trigger. The mine has a simple open sight on the top of its casing to allow it to be aimed in the desired direction when setting up, and notably has the words "FRONT TOWARD ENEMY" embossed on the front. The Claymore is primarily designed for use in ambushes and as an anti-infiltration device against infantry. It can also be used against unarmored vehicles.