String Action Ruler Gauge ,Forever-direct Guitar Set Up Tool for Electric Bass and Acoustic Guitar Fit for electric guitar, Bass , acoustic guitar,mandolin,banjo,etc With conversion chart of string action at 12th fret printed on one side With scale for string height, for ridge saddle slot depth and for nuts saddles and pole pieces Made of stainless steel which is stable,durable,beautiful and widely used Convenient ,pocket-sized ruler which can take to everywhere you like