Review: SIREN String Action Gauge MARK II

I had previously written a review of the SIREN String Action Gauge back in 2019, as I was extremely impressed with the product.

Very recently, I was contacted by Andrew Brown, one of the “SIREN Music Accessories” company owners. He’d run across my review of their original gauge here on the blog (a link to that review is included at the end of this post), and was wondering if I’d be interested in checking out their new MARK II gauges.

Does a wild bear [expletive] in the woods and wipe his [expletive] with a white rabbit? 😎

He generously shipped them from the Toronto, Canada area (home of Rush!) all the way down here to Florida, free of charge.

There are now two flavors of this product available (ref. bottom of packaging):

General Enhancements

  • Radius of the corners have been further rounded to avoid the possibility of scratches.
  • Like its predecessor, all edges are smooth and polished.
  • Thickness has been doubled, making it more durable and impossible to accidentally flex while making measurements.
  • Sharper looking fonts.
  • Leather wallet sporting the SIREN logo is now included for protection, a very welcome addition.

Introducing the brand new “64ths” inch version...

Like nearly all gauges of this type, height bars on the original version were marked in decimal thousandths of an inch, which required a conversion to fractions using the chart on the flip side. This is due to most U.S. guitar manufacturers using 64ths of an inch as their primary unit of measurement for suggested settings of items such as string and pickup heights.

Suggested string height specifications from the Fender Stratocaster set-up manual

You never wind up with an exact measurement in doing so (for example, 4/64″ = decimal 0.0625″, or 1.588mm). While close, it’s much more desirable for the height bars to be scaled and marked in 64ths of an inch in the first place, which also eliminates the need for a conversion.

SIREN’s main goal was to address this customer demand, making it simple to perform height adjustments using these fractions.


  • Distance between the height bars and their top labels has been increased to avoid blocking the view of strings.
  • Width of its smaller side-scales have been widened for clarity.


  • Millimeter scale graduations are now marked as such (versus centimeters).
  • Inch scale guides for 1/8″, 1/16″, 1/32″, and 1/2mm clearly indicated as dashed lines.

Updated “thousandths” inch version…

Still available for those who prefer to stick with decimal measurements, it has also received all of the improvements listed above.

Slide for front/rear view

What’s remained the same as their original gauge, all great features:

  • Black with laser-engraved markings which will never wear off provide a nice contrast for distinguishing strings from gauge labeling. All others I’ve used in the past are unfinished and silver in color with black printed-on text, making it much more difficult to see measurement graduations clearly.
  • Stainless steel construction.
  • Fractional/decimal inch and millimeter conversion table on the flip side.
  • All millimeter scales have been retained.
  • Various short-end scales allow easy access into tight areas.
  • Accommodates string, pickup, acoustic bridge saddle and nut slot depth measurements.
  • A convenient, single gauge for all types of stringed instruments (Guitars, Basses, Ukuleles, Banjos, Mandolins, and others).

Best of all, even with these numerous improvements and the inclusion of a superb quality wallet, its modest asking price ($7.95) is still exactly the same as the original version.

Considering the design, craftsmanship, and materials of these products, they’ll likely last a lifetime. Without a second thought, I’d pay triple that price… Honestly, these gauges are that good!

Andrew’s offer to me couldn’t have had more perfect timing, as I’d recently been having issues with my Stratocaster staying in-tune, especially when using the tremolo bar extensively. Since my wife may have been a bit upset if I took out a second mortgage on the house in order to afford a Floyd Rose locking tremolo system, I went the cheap route to help rectify that situation:

  • Added a 4th tremolo spring and brought the bridge down close to decked, but still floating.
  • Installed slightly heavier gauge strings (D’Addario NY-XL 10/46, another outstanding product, by the way).

Following this, of course the guitar needed to be set-up from scratch. The new MARK II 64th inch gauge made that a piece of cake in all the usual, critical areas.

I’m certainly no Luthier, but even so, most notably it allowed me to perform a complete top to bottom set-up of the guitar in a mere 15 minutes. It now plays like butter, with absolutely no buzz all the way up and down the fretboard.

At that point, I couldn’t resist also testing it on my Fender Jazz bass and Gibson Les Paul Studio guitar. Like the Strat, setting these up required next to no time to complete, each with the same great results.

L-R: Fender Stratocaster, Fender Jazz, and Gibson Les Paul Studio guitars
Click to enlarge

My sincere thanks once again go out to Andrew and the SIREN company, keep up the great work!

I’m totally sold on your products, along with the impeccable customer service you always provide. You truly stand behind them, which is a rarity nowadays.

Looking forward to more from SIREN in the future!

Amazon product pages for each of these new gauges:

SIREN String Action Gauge Mark II – 64ths Inch String Height Scale
SIREN String Action Gauge Mark II – Thousandths Inch String Height Scale

Related links:

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