Ratio Tuned Machine Heads are the first and only machine head to incorporate the different string gauges into the tuning equation. The gear ratios range from 12:1 to 39:1, specific to the relative core size of the string being spun on each, resulting in a consistent response across all strings. One half turn is a semi-tone; one turn is a tone.

Installation is unprecedentedly simple, as each set of Ratios comes with four full sets of Invisomatch mounting plates. In most cases, whatever the current hole profile under the old tuners - one or two screws, 45 degree, 90 degree, etc - one need only position the appropriate plate between the tuner and headstock, utilizing the existing screw holes with no drilling or filling required.

The PRL-8721-C0 is a set of Ratio Locking Tuned Machine Heads for an electric guitar that uses six in line tuners. It has a contemporary mini shaped button, has a two pin casing and is finished in chrome.

Includes InvisoMatch Standard Mounting Plates for easy installation. Fits most headstocks.