Box Filters The box filter is used by many hospitals, research and manufacturing facilities as the final stage in a filtration system. The filter is available in 65%, 85% and 95% efficiencies. Manufactured in either a 6" or 12" depth, the filter has an extended surface area and is capable of providing long service life. The media pack consists of fiberglass paper and aluminum separators. The media pack is sealed into the filter frame to strengthen the filter and prevent air bypass. A 24x24x12 filter will have 137 sq.ft. of media. A 95% 12" deep filter will have an initial resistance of 0.62" w.g. at 500 fpm. The filter is available with either metal or wood cases and with or without a header. The filter can be used in a side access housing or in individual holding frames. A high temperature version is available.