Air filter foam is classified into 8PPI100PPI Polyethylene (Ester, Ether) by size of cell. It is used for every home articles. 8 34PPI : Air conditioner, Ceramic Filter, Dry stand for Aircraft fuel tank, vacuum cleaner filter. 40 50PPI : Small engine, Evaporative cooler, Automobile brightener (Wax), Ear Phone, Stereo Speaker etc. 55 85PPI : Medical equipment, Paint Spray, Booth, Spongy-gourd, Bathing towel, Filterof oil refinery, Power puff, Fuel tank etc. 95 100PPI : Motorcycle air filter, Power puff, Filter of oil refinery, Fuel tank etc.