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6-In-Line Ratio Lefty Electric Locking Machine Heads Staggered Posts (PRL-9721-L, Select Finish and Button)

6-In-Line Ratio Lefty Electric Locking Machine Heads Staggered Posts (PRL-9721-L, Select Finish and Button)



Regular price $160.94 USD
Regular price Sale price $160.94 USD
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Select Finish
Select Button Style

RATIO® patented gear technology
RATIO® - Calibrated 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.

RATIO Machine Heads explanation video

The PRL-9721-L is the left-handed set of Locking RATIO® Calibrated Machine Heads for electric guitars that use 6-in-line tuners with staggered posts (eliminates the need for a string tree).

It has a two pin casing that can be used as is, or with our Patented InvisoMatch Mounting Plates [opens in new tab].

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.


6-in-line tuners set Staggered tuners set Ratio Tuned Machine Heads: The New Standard In Tuning Technology


Gear ratio: unique for each string position - one turn-one tone
Peg holes diameter required: 13/32" (10mm)
String post diameter: 0.236" (6mm)
String post length to string hole: 0.827” (21mm) - 0.787" (20mm) - 0.748" (19mm)
Weight per single machine head: 0.083lbs (38g)
Weight per set of six: 0.496lbs (225g)
String diameter up to 72 gauge
Includes 6 machine heads, mounting screws and bushings
Includes complimentary 4 sets of aluminum mounting plates


Staggered Ratio Measurements.pdfRatio Installation Guide.pdfRatio Installation Guide Video



Reviewed in the United States on February 16, 2020

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