This is a guitar neck straightness measuring tool great for measuring neck curvature and adjusting the fretboard. Make of alloy and electronic components, the digital guitar ruler ensures durability and reliability with long terms use. This versatile tool set is not limited to electric guitars, but can also be used for other stringed instruments that require calibration or repair work to meet the needs. Great tool for measuring neck curvature and adjusting the fretboard, a necessary tool for guitar calibration and maintenance. Compact enough to be handheld, but large enough to provide accurate readings.