GIGmate String Action Gauge Gauge to measure string height, bridge saddle height, saddle slot depth, pickup polepiece height, fret slot depth and nut height. Stainless Steel Rule for electric guitar, bass and acoustic guitar and any stringed instrument. Both mm and inch measurement. See images for full scales. Progressive string height scale, slide across the frets and read the measurement under the string Back of the gauge has a handy fractional/decimal/metric conversion chart. Great all round ruler/ gauge with multiple uses. 85.5mm x 54.0mm