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 the need for visual estimation, allowing accurate adjustment of neck curvature to help address issues such as fret buzz or string breakage. Instructions for use: Digital display advantages: Easy-to-read data with clear numerical values. Pointer model advantages: Compact design and user-friendly 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 and ensure both feet are resting on the frets. A negative reading indicates a concave fingerboard, while 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 models: First set the large needle to zero. When measuring, note the position of the small needle (revolution counter). Subtract its base value from the final reading. Each full rotation of the large needle advances the small dial by 1mm (1 division). For example, if the large needle points to 9, the measurement is 0.09mm; if it points to 90, it is 0.9mm. The small dial indicates millimeters, with each division equal to 1mm. If the small needle moves 2 divisions and the large needle points to 43, the total measurement is 2.43mm. Size: 30x4x1.1cm Material: Metal Color: Black Package Contents: 1 x Neck Curve Dial Meter Note: Light reflection and differences in display screens may cause slight variations between the product color shown and the actual item. Measurement error allowance: +/- 1-3cm.