Grover 102BN Original Rotomatics with Round Button - Guitar Machine Heads, 3 + 3 - Black Nickel, guitar machine heads, Original Rotomatics, closed gear, ratio: 14:1, 6 pieces: 3x left, 3x right, axis diameter without mounting sleeve: 6 mm, mounting sleeve diameter: 10 mm (0.391""), Black Nickel Finish