"Cross Flow Fan" In addition to these two figures, there are two optional letters: Additional letters: prevent access to hazardous parts: A hand, B finger, C tools, D wire. Supplementary letters: special supplemental information. H high-voltage equipment, when M waterproof test sample run, a sample static, W S climatic conditions do waterproof test. Attach an electronic schematic Association IP rating is given, can be more intuitive level have seen these characteristics. Calculated cooling fan product life belongs feel more professional knowledge, here on the right knowledge to do a brief introduction.