Pozi #3 is the ski industry standard for binding mounts. On G3 bindings we take that even further and use only Pozi #3 for everything - mounting, sizing, release values, etc. This is the one tool you need.
This stout screwdriver with a co-moulded handle and hardened tip has been built to stand up to the demanding needs of professional shop techs, but is a great addition for any ski tool kit.