This is the pre-filter for the Health Pro Series air purifiers. This pre-filter (F1) filters of coarse and fine particulate matter and provided pre-filtration for subsequent filters. Media consists of non-woven microfiber, mini-pleated for high-capacity, non-off gassing separators. Efficiency is rated at ≥ 55% at ≥ 0.3 microns (EN 779 class F8). Covers a surface area of 30 sq.ft. (2.8 m²). Average filter life is 18 months (based on average daily usage of 10h on speed 3).