Gotoh Stealth Guitar Machine Head Chrome (3 per side) Mounting hardware included. Gotoh Stealth Keys are the smallest and lightest tuning keys in the world! They weigh in at only 11.9 grams (.026 lb) each! That's the equivalent of only 1/2 to 1/3 of the weight of most standard guitar machine heads. These machine heads let the instrument truly sing by allowing it to resonate to it's full potential and reduces the weight of your guitar significantly. These little guys can stand the test of time. Featuring an 18:1 Gear Ratio (Micro Worm Gear).String tension must be less than 20kgs or 44 lbs, Standard light gauge strings are recommended.