This is the leash DMM used to fit to their more technical axes.
It has an ingenious loop which can be threaded around the shaft so that as you lift your hand up the leash opens allowing you to take your hand out. Alternatively the loop can be hitched over adze or hammer, either of which methods, in theory, enables you to remove your hand from the wrist loop without having to use the other hand - please note the word "theory"!
Suitable for climbing and alpine axes only with a shaft length of up to 55cm long.