1.1. Clean the measuring surface before use and correct the zero position. 0 25mm direct alignment zero: 25mm above use the bar gauge aimed at quasi zero. 2.2. Zero correction method: If the 0 bit line is not aligned with the baseline, first loose screw with a screwdriver slightly, with a wrench to adjust the baseline position, so that the baseline alignment 0 taste bit line, then tighten the screws. (See instructions for use picture 2) 3.3. When measuring, the micrometer should be perpendicular to the work piece under test, rotating force measuring device, the measuring surface in contact with the work piece should be rotating gently, when the force measuring device issued a slight 'click, click...' sound, That is the actual size of the work piece under test. 4.4. Locking device can be passive measurement of micro screw back and forth. Relax to the right and lock to the left. (See instructions for use Figure 3)