This is a must accessory for any lazy guitarist out there, just pop it into your electric drill and bzzzzz! your old strings are no more, bzzzz! again and the new string is in place, exactly 1,5 second after. It's a lifesaver and I wish someone told me about it on my first guitar lesson, it resembles a washing machine - it turns an otherwise boring, tiring and straight awful procedure into noisy, fast and efficient action.
Best. Thing. Ever.