Multi-Pocket filter The perfect choice for air conditioner ventilation system. The fiber media can hold a large quantiy dust. The efficiency is stable in the whole life-span. Optimized V-collector structure has low resistance and long life-span. The average efficiency is 45%,65%,85% and 95% by colorimetry( ASHRAE52.1-1922) Filtration efficiency grade: F5,F6,F7,F8,F9 (EN779).