Graphtech Ratio 6-In-Line Electric Guitar Machine Heads Classic Black PRN-2731-B0 

A right-handed set of Ratio Calibrated Machine Heads for electric guitar that use 6-in-line tuners. It has a two pin casing that can be used as is, or with our InvisoMatch mounting plates. 4 Sets of InvisoMatch mounting plates in brushed aluminum are included to make installation on most guitars fast and accurate by using your existing screw mounting holes. 

Ratio - Tuned Machine Heads incorporate different string gauges into the tuning equation. From Low E to High E 39:1, 24:1, 20:1, 35:1, 20:1, 12:1. We balanced the gear ratios to each string simplifying the tuning process. With Ratio, a half turn is a semi-tone! Every string reacts the same to any tuning adjustment. Predictable, precise tuning, on every string.