Desiccant refers to a substance that can remove moisture from moist materials. It is often divided into two categories: chemical desiccants, such as calcium sulfate and calcium chloride, which are dried by combining with water to form hydrates; physical desiccants such as silica gel and active alumina or the like is dried by physically adsorbing water. Desiccant often made into desiccant bags, desiccant packs. The control of moisture is closely related to the yield of the product. In the case of food, bacteria and mold in food will multiply at an alarming rate under appropriate temperature and humidity, causing food to spoil, causing moisture and discoloration. Electronic products can also cause oxidation of metals due to excessive humidity, which can cause defects. The use of desiccant is to avoid the occurrence of defective products caused by excess moisture such as cargo desiccant.