Graph Tech PRL-8721-B0, Locking Machine Heads for Electric Guitar, 6 Pieces for 6-in-line arrangement, Bass Side/Right Hand, Incorporate string gauges in tuning equation, half turn equals half tone on each string, Quicker and more accurate tuning of each string, Thumb wheel screw on the back for locking the string, Contemporary tuning buttons, Closed construction, 2-Pin mounting, Mounting hole diameter: 9.7 mm, Axis diameter: 6 mm, Ratio E - 12:1, B - 20:1, G - 35:1, D - 20:1, A - 24:1, E - 39:1, Colour: Black, Incl. InvisoMatch standard mounting plates for the use of existing screw holes