SINCE 2010



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Aluminum, steel, brass

Overall dimensions             mm 200x20x36

Base dimensions               mm  200x20

Works straight or with relief

Works with strings on or strings off

Adjustable relief

2 models: Straight or Radiused 


Coming soon


Tired of guessing how to perform a fret leveling in playing condition without the relief?

We have the solution! MONSTER RAIL mini has the adjustable relief. It can perform precision fret level with the neck straight or with the relief, with the strings on or the strings off. It is well known that having the strings on might not be enough to ensure the ultimate fret leveling. When the truss rod is adjusted to set the neck straight while attempting to perform a string tension fret level with a straight tool, some forces are changed and the neck shape as well. That might not reflect the actual playing condition anymore. As a consequence, a fret leveling that might be convincing while it is being carried out might result in a less than perfect job when the instrument is put back in true playing conditions with relief and a last setup. That is why we have created the adjustable relief fret leveling beams. No more guessing! You can now level your frets in full playing conditions ...and position!

Still not confident enough to level the frets without a radiused tool?

MONSTER RAIL mini comes with the base planar or with a built in radius. The version with the radius can help to achieve a more consistent radius on the fretboard, fingerboard or the frets when the leveling operation is performed by a beginner or someone who still doesn't have enough confidence to perform a leveling operation on a radiused fretboard without a radiused tool.


Coming soon





RR Kit (reload/refinishing kit)

Reload And Refinishing Kit is all you need to reload the leveling tool and crown the frets after leveling them with one of our systems. The file in the Kit typically covers two or more fret level works. LittleBone #150 grit would last more than the LittleBone #400 grit but it would also leave deeper marks to refinish. Advise when you contact if you prefer LB150 in your Kit, instead of the LB400.


It contains:

-1 LittleBone Fret File #400grit

-1 roll 0.64mm x 2.9m self-adhesive abrasive #320 grit for reloading and refinishing that will replace the little roll coming with the stand alone tool

-2 Masking size of masking tape for fretboard protection (9 mm and 18 mm)

-1 abrasive fiber #600 grit for refinishing




*Kit is sold only with one of our fret leveling tools for additional US$38.

Luthier tools


    KATANA FRET LEVELING SYSTEM is a system designed for leveling the frets, or the fretboard, under real strings tension Read More
  • BUZZ Killer

    More information about this invention: Reference fret level For all instruments - 132 mm This innovative tool Read More
  • Rocking File

    The Rocking File™ is a special tool designed to check and fix the height of your guitar's frets while Read More

    Tired of guessing how to perform a fret leveling in playing condition without the relief? We have the solution! Read More
  • LittleBone Fret File

    LittleBone fret file helps to reshape frets worn by use or flattened out after fret leveling. LittleBone Fret File is Read More
  • RR Kit (reload/refinishing kit)

    RR Kit (reload/refinishing kit) can be purchased only with a fret leveling tool like: R.M.KATANA, R.M.LITE, R.M.BUZZ Killer. Read More
  • LittleBone ice

    LittleBone ice is bigger than the classic LittleBone Fret File. It is easier to hold. It lasts longer because Read More

    Say Hello to the new born 2 Corner fret file! This new tool is quite foolproof. It is aggressive Read More

    By Inventor Davide Bissoli here is a new tremolo stopper for guitar setup and repair. The TREM GUARDIAN is Read More

    DRAGONCLAW is a tuning tool designed to operate on Floyd Rose Tremolo. It was designed to leave the area Read More
  • Digital Action Gauge

    With this device you can measure the Action of the strings and the neck Relief with no need… Read More

    FRETBLADE™ is a special fret leveling tool that includes: Reference fret level, Adjustable relief, Single fret and spot level Read More

    Understring Crowning File is a proper fret crowning file designed to work underneath the string without altering the playing Read More

    UNDERSTRING FLK mini is a system designed for spot leveling the frets, or the fretboard, under strings tension. Fret Read More

    This tool is similar to a LittleBone for small or very small frets like those often installed on ukulele Read More
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Price list

REMINDER: to buy our tools please make sure to visit the How to buy page first. Thank you 

Prices are in USD

Final shipping price may vary depending on volume, weight and final destination of the order.

International shipping price is minimum $32. At the moment most destinations are covered by EMS which is quality service but it can be more expensive than certain other services that we have been using until a few years ago which aren't available at this time.

*There might be some lower prices for those Countries that still offer economy shipping services. Please let us know where you buy from so we can check the latest shipping options and prices for your Country.

RED is out of stock

RR Kit is accessory (sold only with a leveling tool)

R.M.KATANA for guitar $220 +Shipping  $32
R.M.KATANA for guitar Limited Edition 440mm $195 +Shipping  $32
R.M.KATANA for bass $255 +Shipping  $42
R.M.nanoKATANA *uke $145 +Shipping  Ask
R.M.BUZZ-Killer single fret and spot leveler  $80 +Shipping  Ask
R.M.LITE for guitar  $40 +Shipping  Ask
R.M.LITE for bass  $55 +Shipping  $38
Rocking File  $18 +Shipping  Ask
C-File --- --- ---
UNDERSTRING FLK mini  $59 +Shipping  Ask
RR Kit (reload/refinishing)  $38 Accessory  
LittleBone #400 grit  $20 +Shipping  Ask
LittleBone #150 grit  $24 +Shipping  Ask

LittleBone DoubleAngle #400 grit

 $28 +Shipping  Ask
LittleBone DoubleAngle #150 grit  $28 +Shipping  Ask

LittleBone DoubleGrit


 $28 +Shipping  Ask
LittleBone ice #320 grit  $28 +Shipping  Ask
LittleBone ice #150 grit  $28 +Shipping  Ask
LittleBone ice DoubleGrit  $42 +Shipping  Ask
LittleBone ice Special  $38 +Shipping  Ask
Digital Action Gauge  $42 +Shipping  Ask
FRET RAIL mini  $16 +Shipping  Ask
Feather File for nut   $20 +Shipping  Ask
BOOMERANG FRET FILE  $46 +Shipping Ask
TREM GUARDIAN  $38 +Shipping $15
DRAGONCLAW  $28 +Shipping Ask


About Rectify Master

RECTIFY Master focuses on research and development of innovative and quality luthier tools. Setting new standards since 2010. With over 30 year experience. Beware of imitation.

TOKYO, Japan

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