We have a variety of different backing plates to suit an array of different harness styles. Does not include an A4043 handle. The Keyball System: For many years the Allen development team were keen to design a trapeze system that improves the safety of the sport and reduces the risk of entrapment by the traditional hook-on trapeze harness. Designer Julian Bethwaite had also been thinking along the same lines and had produced a prototype of the Keyball trapeze system. In conjunction with Bethwaite Design, Allen has developed the concept into a sleek and innovative design, eliminating the hook and creating a safe intuitive solution that works. The Allen Keyball system removes the traditional hook from the trapeze harness and replaces it with a moulded plastic socket. The Keyball socket has no sharp edges or protruding parts meaning there is a reduced risk of entrapment for the user. By wearing a Keyball harness you will also limit the chances of damaging the equipment on the boat, users are less likely to rip the sail or pierce the deck/hull of a boat because of the lack of pointy edges. Click here to see our range of fully assembled Keyball trapeze harness systems.