The ruler should not be mixed with a knife or metal stationery. When mixed with a pen, the pen cover must be put on. The ruler has sharp parts. Pay attention when using it to avoid scratching. Be sure to prevent exposure to the sun and long-term sunshine, and keep away from kindling, so as not to affect the accuracy of the measuring instrument and cause danger. It is better not to clean the ruler with a brush.

Rulers used in different situations have different requirements and standards. If the value is more accurate, it requires higher technology and must be produced by machine. In addition to the requirement of accurate value, the second key is the quality of the engraved value. Generally, a protective film will be applied after the engraved value. The third point is the selection of materials, which are now divided into plastic, metal and wooden rulers, Plastic rulers are mainly used for stationery by ordinary students, metal rulers are more used in industry, and wooden rulers are mainly used for teaching.