V-Type Mini-pleat Medium Filter The glass fibre is water-resistant. The polypropylene plastic frame can be disposed by incineration. It has big filter area, low resistance and long life-span. Its thickness is 290mm, which is suitable for the ventilation air condition systems that the space for installation is limited. The HEPA filter with flanges and multi-pocket filter can be use in interchange. The average efficiency is 60%, 90%,95%,98% by colorimetry (ASHRAE52.1-1922). Filter efficiency grade: F6,F7,F8,F9( EN779).