Akface Guitar String Action Ruler Gauge Tool Measuring Kit for Electric Bass and Acoustic Guitar Double sided, Imperial (inches) One Side, Metric (millimeters) On The Other. With Conversion Chart of String Action at 12th Fret Printed. Each gauge is printed with a useful decimal and metric conversion chart. It's easy to read so checking and adjusting string action will definitely be a breeze. Perfect accurate action measurements for string instruments such as guitar, bass, mandolin, banjo, etc Pocket Sized, Convenient for Taking to Everywhere You Like Ruler size:8.9cmx5.1cm/3.5''x2.0''(LxW)