Perfect Shield is the most effective odor blocking cover in existence, with aluminum as the main material, corrosion resistance, workability, lightness, rigidity, non-toxicity, cryogenic resistance, resulfurization, and aesthetics. Aluminum alloy is resistant to corrosion by forming a protective oxide film when it comes into contact with oxygen and has a semi-permanent lifespan of more than 40 years. In addition, it has excellent heat reflectivity to prevent the water temperature from dropping even when the outside temperature is below zero.