Graph Tech PRN-2411-C0, Machine Head Set for Steel String Guitar, Style: 3 Left / 3 right, String gauges were considered in gear ratio: Half a turn corresponds to 1 semitone per string, Faster, more accurate tuning of each string, Contemporary buttons, Closed construction, 2-Pin assembly, Mounting hole diameter: 9.7 mm, Shaft diameter: 6 mm, Gear ratios: E - 12:1, B - 20:1, G - 14:1, D - 20:1, A - 24:1, E - 39:1, Finish: Chrome, InvisoMatch standard mounting plates included for using existing screw holes