Outer diameter micro-meter the external dimensions measuring instruments, measure the distance between the two sides of the square frame by use of helix principle. Outer diameter micro-meter is mainly used for measuring a variety of external dimensions. Diameter micro-meter dividing value is 0.01mm, the upper limit of measurement range is not more than 300mm, divided into a 25mm per specification. Such as 0-25mm, 25-50mm ...... and so on. Measuring range: 0-25 Resolution: 0.001 Instructions for use: 1. Clean the measuring before use and correct the zero position. 0-25mm direct alignment zero: 25mm above use the bar gauge aimed at quasi-zero. 2. Zero correction : If the 0-bit line is not aligned with the , first loose screw with a screwdriver slightly, with a wrench to adjust the position, so that the alignment 0 taste bit line, then tighten the screws. (See instructions for use picture 2) 3. When measuring, the micro-meter should be perpendicular to the work piece under test, rotating force measuring device, the measuring 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. Locking device can be passive measurement of micro-screw back and forth. Relax to the right and lock to the left. 5. When measuring, the left hand should hold the heat shield to prevent body temperature transmitted to the micro-meter, causing measurement error. 6. One end of the wrench can be adjusted zero, the other end can pull the force measuring device. Colour:As Shown Material:carbon steel Package Contents: 1 x Outside Micro-meter 1 x Accessory 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.