... has big filter area, low resistance and long life-span. 2)Its thickness is 292mm, which is suitable for the ventilation air ... condition systems that the space for installation is limited.3)The HEPA filter with flanges and multi-pocket filter can ... be use in interchange.4)The average efficiency is 60%, 90%,95%,98% by colorimetry (ASHRAE52.1-1992).5)Filter ...