The AltairSystem3 range of filter elements consists of the OHB pre-filter and a range of OHF high efficiency filter options. The high efficiency elements are interchangeable and offer superior filtration and coalescence performance with pre-filters. Features & Benefits OHB The OHB pre-filter is used to increase the dust-holding capacity of the system and the life of the high efficiency filter elements leading to extended intervals between shutdowns. Available in G3 and G4 filtration efficiency. OHF High efficiency final filter, based on pleated media in a rigid, molded V-cell frame. Offering excellent filtration efficiency with outstanding sub-micron particulate and droplet removal efficiency. Available in F9, H10 and H11.