MusicNomad TRI-BEAM-NOTCHED 3-in-1 Straight Edge Tool w/2 Notched & 17.6in SidesDiagnosing how level your frets and fretboard has never been easier with MusicNomad's patent pending Tri Beam Dual Notched and Precision Straightedge. Creating a new higher standard, our unique 3 wall triangle design gives you two notched straight edges custom designed to cover more fret scale lengths ranging from 24. 625" to 25" and 25. 34" to 25. 625" to measure the flatness of your fretboard and neck relief. Rotate to the 3rd side to use the 17. 6"