Laser speed guns transmit short bursts of invisible light which bounce off a target vehicle and return to the laser gun. By timing the outgoing and return trips of the light bursts, it can compute the target's speed. The laser's biggest selling point is its narrow beam-only about three feet wide at a distance of 1,000 feet-a feature that provides nearly foolproof target identification. (In comparison, a radar's beam is about 250 feet wide at 1,000 feet.) Laser guns must be used from stationary position and are most effective at short range, usually when targeting traffic at 700 to 1,200 feet.