Graphtech RATIO 7-STRING Electric Locking 4x3 Contemporary Black 2 Pin PRL-8521-B7

The PRL-8521-B7 is a 7 String set of Locking Ratio Tuned Machine Heads (Black finish) for electric guitar that use a 4x3 Configuration. It has  has a two pin casing that can be used as is, or with our Patented InvisoMatch Mounting Plates. 4 different 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 B to High E 48:1, 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.

Standard Machine Heads - Installation Guide
Standard Machine Heads - Actual Size Template & Dimensions

InvisoMatch Mounting Plates - Actual Size & Dimensions

THE SIMPLE GENIUS BEHIND RATIO¨ TUNED MACHINE HEADS

We've tuned the gear ratios to each string position so that every string responds the same to any tuning adjustment. You get fine tuning on the thicker core strings and coarser tuning on the thinner core; anywhere from 12:1 to 39:1 gear ratio. With Ratio¨, one turn is about one tone change on all strings, making tuning, retuning and open tunings easier, quicker and more intuitive.

PREDICTABLE, PRECISE TUNING, RETUNING AND OPEN TUNINGS.

Ratio¨ tuning feels natural. You don't have to think about which string you are tuning because they all feel and respond the same. No more overshooting the Low E or G. No more twisting away on the High E or D string. Open tunings have never been easier. String gauges such as light top, heavy bottom are no problem with Ratio¨; they still do the same precision tuning.

NOT JUST ANOTHER MACHINE HEAD.

Ratio is more than just another entry into the machine head market. Instead, Ratio has reinvented how machine heads function with the musician.

Installation Video