Ernie Ball Power Peg
The Ernie Ball Power Peg is so simple and so useful that you'll never go back to wearing your fingers out restringing guitars. The Power Peg fits virtually any tuning key, including bass, and turns in forward or reverse. You will cut your restringing time by up to 70%. A locking switch prevents accidental operation. Plus, the battery operated Power Peg is extremely portable.
4 AA batteries