Amazon.com: StewMac String Action Gauge And Ruler, Metric, Stainless Steel - Designed by StewMac, The Original measuring tool for acoustic and electric guitar, and bass setup : Musical Instruments
Amazon.com: Bnineteenteam Guitar String Gauge Tool,Measurement Standard String Action Ruler Gauge with Fret Protectors Set for for Electric Guitar Acoustic Guitar Bass and Luthier Performance Accessory : Musical Instruments