Well ... I have a chain type "key-back" which has the straps flat with holes for mounting with screws to the side of the head, and a strap around a turned-down section of the key body so it will turn inside the chain. It also has a spring around the pilot. The combination makes sure that you can't leave the key in the chuck and turn it on. :-)
Not that I have used it for years. I've got a very nice precision keyless chuck in there instead. (It is a Jacobs implementation of the Albrecht design.)
Enjoy, DoN.