There may come a time when you have to let go of your kite- perhaps the wind suddenly picks up and you're unable to control it or perhaps you simply miss a move and fall, letting go by accident.
A fully powered up kite out of control on a beach is no laughing matter- the potential for injury to passing people is high and you also run the risk of damage or loss to your valuable kite. Kite Killers are a system to retain your kite in the event that you let go of the handles. They act by linking the brake lines of the kite to the pilot via wristbands, so if the handles are released the brake lines are brought into use to de-power the kite and allow it to land safely. The pilot can then pick up the handles and relaunch the kite safely, or pack it away and go tell all his friends about his narrow escape!