How does it work?
1. Check the table on the back of the product and choose the corresponding size according to the type of instrument, e.g. electric guitar, acoustic guitar, bass guitar, etc.
2.The table has the corresponding 1-string and 6-string heights (the height of the 12th fret) in both inches and MM units of measurement. Read the height value from the bottom of the string by looking at it sideways and flat.
3. Compare the actual measurements and make adjustments. You can adjust the neck curvature and the height of the bridge nut and saddle for optimal hand feedback.
4.Repeat this step for the other strings on the guitar you need to measure.
5. For an example of the operation diagram, you can check the operation manual.
Features:
1.Fit for electric guitar, Bass , acoustic guitar,mandolin,banjo,etc.
2.With conversion chart of string action at 12th fret printed on one side.
3.With scale for string height, for ridge saddle slot depth and for nuts saddles and pole pieces.
4.Made of stainless steel which is stable,durable,beautiful and widely used.
5.From inch fractions, to inch decimals, to metric in increments.

Specifications:
Material: Stainless Steel
Color: sliver
Application: electric guitar, bass , acoustic guitar etc.
Unit: mm/ in Scale for string height: 0.01-0.14in / 0.25-3.50mm Scale for bridge saddle slot depth: 0-0.875in / 0-20mm Scale for nuts saddles and polepieces: 0-0.75in / 0-20mm
Ruler size: 8.9 * 5.1cm / 3.5 * 2in (length * width)
Ruler weight: 28g / 0.99oz

Package including:
String action ruler *1
Instruction paper card *1
Leather Case *1
Bone Nut *1
Bone Saddle *1
Guitar pins (White) *6
Guitar pins (black) *6
Pin puller *1