Primary Efficiency Pleated Industrial Air Filter G1 G2 G3 G4 Efficiency (With Aluminum Alloy Frame) Product Description This industrial air filter features a foldable structure that significantly increases the effective filtration area (3-5 times more than flat-type filters). This design reduces wind speed on the filter material, extends service life, and lowers system resistance. Filtering efficiency: 5 micron accuracy, meeting European standards G1/G2/G3/G4 with ≥95% weight