Therefore, we usually use the four-week measurement (vertical line at 2/4/8/10) to understand the beat value of the racket. How to use: In the step, rotate the disc in the reverse of the hands of a watch to set the scale to zero In the second stage, the small cylinders pressure measuring device are perpendicular to the surface of the drawing surface and inserted into the transverse In the third step, turn the pressure gauge into the hands of a clock. When the vertical line is placed in the arrow pressure gauge, just find the corresponding dial scale value. Note that the beat value is not exactly the same as the sharp value, but some points tend to be pounds. Color: Black Material: PVC. Contents: 1 x voltage calibrator. Only the above package, products are not included. Note: Due to lighting and different screen settings, the colour of the item may vary slightly from the actual product. The allowed measurement error is +/- 1-3 cm.