Product name: neck curve dial meter Product function: This high-precision neck flatness dial meter can measure the deformation and bending of the neck, so that there is a very reliable and clear measurement standard to judge the deformation and bending of the neck. It does not need to rely on the eyes to see, to adjust the bending and deformation of the neck, so that quickly adjust the flatness of the neck to the problems of breakage and noise and so on Instructions for use: Digital display advantages: more convenient to view data, but also more clear and easy. Pointer model advantages: compact and easy to operate. 1. First, adjust to zero on the glass or other pure flat , place the tool on the glass, loosen the screw in the upper right corner of the dial, and turn the large needle dial to zero, fixing the base to 0. If it is a wooden guitar, push the top to the 12 pin thread, and the feet at both ends also on the pin thread. If the pointer is negative, it indicates that the fingerboard is concave. If it is a positive number, it indicates that the finger board is convex. Adjust the steel bars in the neck of the piano. The closer the value is to zero, the better. Similarly, digital displays are also used, but the numerical values are more pronounced, Pointer style description: The large needle first turns to zero, and when measuring, confirm the base of the small needle first. After it is in place, subtract the base from the index. The large needle rotates once, and the small dial rotates 1mm (1 grid), representing 1mm. For example, if the large needle points to 9, it represents 0.09mm, and if it points to 90, it represents 0.9mm. The small dial represents mm, and 1 grid is 1mm. If the small needle turns to 2 squares and the large needle points to 43, the data is 2.43mm size: 30x4x1.1cm Material: Metal colour: ver Package Contents: 1 x neck curve dial meter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +\/- 1-3cm.