This is a great bit of kit when you need to change from from one hand to the other frequently as in tight twisty bits. Better than the traditional around the wrist type leash at least on a walking axe.
I purchased two single spring leashes. Although this works out to be slightly more expensive than a double leash, it offers more flexibility. One leash is ideal for an easy, axe-only day, or both leashes for when two axes or an axe and hammer are needed