The RockCare Rock n' Ruler is a versatile Tool for setting up your guitars and basses. String action, neck relief and string spacing can be easily measured and set up with this simple gauge. All scales are provided in metric and imperial units, so no conversion is necessary. The backside offers useful setup recommendations as a starting point for setting up your electric, acoustic or bass guitars. With its handy business card size it easily fits into your wallet and is always with you, when you need it.