Exceptionally Precise Tuners You Can Rely On Choose Grover Roto-Grip Locking Rotomatic tuners for exceptional tuning stability and long-term reliability. Roto-Grip Locking Rotomatics feature a precise 18:1 ratio, as well as a locking mechanism that keeps your strings securely in place. Just thread the string through the post hole, wrap it once, then tighten the thumb screw to lock it down. These tuners are an ideal replacement for most standard guitar tuning machines, and come with all necessary mounting hardware and a retro-style keystone look. For stable tuning that’s ultra-reliable, Sweetwater guitarists know to grab Grover Roto-Grip Locking Rotomatic tuners!Grover Roto-Grip Locking Rotomatic Keystone Tuning Machines for Guitar Features: Locking tuning machines for guitar Color: chrome 18:1 gear ratio 0.391-inch hole size 3 x 3 configuration Keystone-style pegs