Primary air filter
The primary air filter has four styles: plate type, folding type, bag type, and box type. The outer frame materials include paper frame, aluminum frame, galvanized iron frame, and stainless steel frame. The filter materials include non-woven fabrics, nylon mesh, activated carbon filter cotton, and metal mesh. The protective nets include double-sided plastic-sprayed wire mesh and double-sided galvanized wire mesh. They are inexpensive, light, versatile, and compact.