40ppi Air Filter Foam: 1)Excellent filte function 2)Reusable,washable 3) ... cutting equipment, can product various shape of foams. 2.40ppi Air Filter Foam detail:1)Material: PU (polyurethane)2)Aperture: from ... ,washable, acid-resistant,alkalifast, Flexible,good tensile7)Use: filter dust, air, liquid, equipment filter etc. 40ppi Air Filter Foam 40ppi Air Filter Foam