Terrible name, but this will be one of your busiest tools! The EZ-Winder is a durable plastic socket that fits most guitar tuning knobs, to make restringing faster and easier. The 1/4" hex stem fits your cordless screwdriver or socket driver. It's a real time-saver.
I use one with a 3.6v Bosch cordless screwdriver - just about the right power and speed.