Fangrui Product Details 1.high Quality - Made Of Stainless Steel With Rounded Off Edge, Anti Rust, Prevent Scratch Or Cutting, And Long Service Life 2.wide Usage - Suitable For Measure All Kinds Of Electric Guitar, Electric Bass, Acoustic Guitar, Electric Box Guitar Fretboard Measured In Radians, Radians To Adjust The Strings Piano Code 3.it Is A Guitar Common Spacing Chord Distance Measure Tool, Chrome Plated Main Shaft For Easy Clean Up And Professional Look 4.can Be Applied To Accurately Measure Fret Board Radius, Saddle Radius Nut Radius From Either The Top Or The Bottom Radius , A Must Have For Bass Guitar Maintain And Adjustment 5.string Action Ruler - Each Gauge Is Printed With A Useful Decimal And Metric Conversion Chart. Provides Precise And Accurate Measurements Not Only For String Action, But Can Also Be Used In Measuring Nut Height, String To Pole Distance And Fret Slot Depth Product Name: Guitar T-shaped Arc Ruler, String Height Ruler Colour: Silver Material: Stainless Steel + Plastic Package Contents: 9 X Radian