The US Army has fielded 8,000 Launched Grapnel Hook systems to infantry and engineer units as a type of mine-clearing device. Another 12,000 have been produced and are held as war reserve stocks. The system weighs three pounds; the hook itself weighs only one pound. The hook is propelled from an M16 rifle or M4 carbine 80-100m by a ball cartridge or grenade-launching blank cartridge. The firer then pulls it back using a cord. The hook will snag most tripwires in the area it covers (94% if done properly) and detonate any associated mines. (The preferred firing position is prone, with the butt of the rifle against the ground and the barrel elevated 45 degrees.) The system uses bullet trap technology, but can only hold one bullet. After used once with a live round, the system can only be used with the grenade-launching blanks, but it can be used indefinitely in this way. (The less powerful standard blank round will throw the hook about 20m, enough for training.) The system is also used by several NATO countries.-Stephen V Cole