Product name: Neck Curve Dial Meter Product function: This high-precision dial gauge measures neck deformation and bending, providing a reliable and clear standard for assessing neck flatness. It eliminates reliance on visual estimation, allowing accurate adjustments to correct neck curvature, improving playability and reducing issues such as string breakage and noise. Instructions for use: Digital display advantages: Easy-to-read numerical output for quick and accurate measurements. Pointer model advantages: Compact design and simple operation. 1. Begin by zeroing the gauge on a flat surface such as glass. Place the tool on the surface, loosen the screw in the upper right corner of the dial, rotate the large needle to zero, and secure the base at 0. For wooden guitars, position the top at the 12th fret, ensuring the feet rest firmly on the frets. A negative reading indicates a concave fingerboard; a positive reading indicates a convex fingerboard. Adjust the truss rod in the neck accordingly. Values closer to zero indicate optimal flatness. Digital models display readings numerically for enhanced clarity. For pointer-style models: First set the large needle to zero. When measuring, note the position of the small needle (main scale) first. Each full rotation of the large needle advances the small dial by 1mm (one division). The large needle indicates 0.01mm increments. For example, if the large needle points to 9, it represents 0.09mm; if it points to 90, it represents 0.90mm. The small dial shows millimeters. If the small needle moves two divisions and the large needle points to 43, the measurement is 2.43mm. Size: 30x4x1.1cm Material: Metal Color: Black Package Contents: 1 x Neck Curve Dial Meter Note: Light reflection and screen settings may cause slight color variations between the image and actual item. Measurement error allowance: +/- 1-3cm.