The Ernie Ball Power Peg Pro is a motorized pegwinder that makes changing strings on your guitar or bass a breeze. Designed to fit the tuning machines of all guitars, basses, mandolins and ukuleles, the Power Peg Pro is 80% faster than manual string winders and infinitely easier than using your thumb and forefinger. A rechargeable lithium ion battery means you'll never be looking for obscure batteries when the Power Peg Pro needs more juice.