These label is widely used in repair service centers in the electrical industry, such as batteries, smart phones, electrical appliances, electronics, LCD monitors, etc. It is difficult to identify whether these products have entered water. In addition, the identification of ocean transportation goods requires it to provide legal evidence when claiming, because When a water-sensitive warning label comes in contact with water, its surface instantly changes from its original color (or a custom color) to its new color and is irreversible