"Cross Flow Fan" IP (INGRESS PROTECTION) protection rating system is drafted by the IEC (INTERNATIONAL ELECTROTECHNICAL COMMISSION). The electrical characteristics according to its dust and moisture proof to grade. Foreign objects referred to herein containing tools, etc can not be a human finger into contact with live electrical parts within, in order to avoid electric shock. In the cooling fan industry, there is often a function of dust and moisture to customer needs, based on different environment, choose a different IP rating. Such as the Association Hengda electronic DFX12038 can achieve the highest level of IP68. IP protection class is composed of two figures, the first number represents the lamp away from the dust, to prevent intrusion of foreign material level, the first two numbers indicate the lamp against moisture, water penetrated the closed level, higher numbers mean more protection grade high.