Specification for air filter paper: 1) Weight: 120-145gsm 2) Thickness: 0.45mm 3) Air permeability (200Pa L/100cm?min) : no less than 330 4) Burst strength (kPa): no less than 240 5) Resin content (%): 20~22 6) Maximum pore size: 80 7) Mean pore size: 40 8) Corrugated depth (mm): 0.25 9) Paper color as requested 10) Roll length and roll inner pore diameter as requested 11) Plain paper or corrugated paper as requested