This is an excellent way to clean and hydrate dark, natural-wood fretboards. The spray bottle is a bit messy, with lots of overspray to undesirable areas, so it is best to mask off the headstock, pickups, and body of the guitar before applying. Use a soft toothbrush to spread the product evenly and scrub the wood, particularly next to the frets, then remove the loosened dirt and excess product with a clean cloth. This contains petroleum distillates, so it offers the best possible cleaning and hydration without the (purported) undesirable side effects of lemon oil. Use sparingly....unlike money and horsepower, too much is worse than none at all.