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4 String 2+2 F-style Bass Ratio - Chrome (PRB-4221-C0)

4 String 2+2 F-style Bass Ratio - Chrome (PRB-4221-C0)



Regular price $195.44 USD
Regular price Sale price $195.44 USD
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RATIO® patented gear technology
RATIO® - Calibrated Machine Heads incorporate different string gauges into the tuning equation.

From Low E to G - 48:1, 36:1, 25:1, and 23:1.

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. 


Bass Ratio animation

The PRB-4221 is a right-handed set of RATIO® Calibrated Machine Heads for BASS that use 2 x 2 configuration.


In order to achieve the higher gear ratio's, Ratio's are the world's first machine heads using a double envelope gear design with a hardened steel gear. Amazingly smooth and super strong.


Headstock Configuration 2 x 2  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: 0.720" (18mm)
String post diameter: 0.547" (13.9mm)
String post length to string hole: 0.807” (20.5mm)
Weight per single machine head: 3.5oz (99.3g)
Weight per set of four: 14oz (397g)
String diameter up to 130 gauge
Includes 4 machine heads, mounting screws and bushings


Staggered Ratio Measurements.pdf Ratio Installation Guide.pdf Ratio Installation Guide Video


Our Bass Ratio rated 5 stars on Sweetwater.

Sweetwater Rating 5.0


Rated 5.0 stars
Based on 1 review
Total 5 star reviews: 1 Total 4 star reviews: 0 Total 3 star reviews: 0 Total 2 star reviews: 0 Total 1 star reviews: 0
100%would recommend this product
1 review
  • PT
    Paul T.
    Verified Buyer
    I recommend this product
    Rated 5 stars
    1 month ago
    Ratio tuners a great upgrade

    It is much easier to tune the E string on my bass since changing the tuners.

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