The Quick Release Box (QRB) is the connection between the winch man and the hoist system of the helicopter.
The QRB is able to open under tension up to 150 kg. Security wise this is a very important ability. If the winch man get into problems, entangledmon a wreckage or stock between rocks, the helicopter has a problem, and the crew could be forced to cut the cable. If this happens for a helicopter equipped with a single hoist, the helicopter is not able to get back to rescue the rescue man, and far the less the victim.
The complete assembly includes P/N 9001 9010 QRB mk-4 and P/N 6008 1470 Suspension Strap. The assy is part of Lite Flites CE type approved Helicopter Rescue System, that also include Hoist Harnesses and a complete Lanyard System.