The package includes 2 Guitar Neck Notched String Measurement Ruler and 2 String Action Ruler. Perfect accurate action measurements for string instruments such as guitar, bass, mandolin, banjo, etc. Guitar Neck Notched Straight Ruler - Made of stainless steel, rustproof, sturdy enough for your long-term use. Size: 16.5 x 1.45 x 0.15 inch, Dual scale design, works well with most guitar, specially suits for (24.75 inch) and for (25.5 inch) electric guitars Ruler - Made of high quality plastic, The ruler is double-sided, there is fraction, decimal, metric conversion chart on back.This guitar string action gauge ruler can measure string height, bridge saddle height, saddle slot depth, fret slot depth and nut height and accurately measure other setup adjustments. The Neck Notched String Measurement Ruler is designed to check guitar neck straightness of the fretboard and frets. Ruler Use To Measure: Nut or String or Bridge or Pickup Pole Piece or Saddle Height Plus Saddle Slot or Fret Slot Depths. Excellent Luthier tool and essential for any guitar technician, or guitarist who wants to look after, maintain and repair their instrument themselves. Colour:Silver Material:Stainless steel and Plastic Package Contents: 2 x Guitar Neck Notched String Measurement Ruler 2 x String Action Ruler Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is 1-3cm.