This is because food, vegetables, fruits and other items with plastic wrap and put in freezer cabinets after, because it is cooled in a sealed package of air, water vapor in the air is not all in the vapor state, that the air is saturated with water vapor water vapor condenses on the film surface into small droplets dispersed, so that the film formed on the surface of the water spray. Fogging shortcomings will affect the transparency of the film, resulting in not clearly see the packaged food, water droplets fall on the food, easy to breed bacteria that cause food decay. There are currently an ordinary plastic wrap and plastic wrap antifogging high, please pay special attention to the time of purchase.