Trapezoidal filters are equipped with a system to guaranty that air drops in a circular crown around the filters in case of air leakage from the gaskets around the filtering Section. Keeping the crown in depression using the re-suction fans, allows for evacuation of the air which is bypassed the HEPA Filter. Above the filters there’s a galvanished steel plenum (accessory: Stainless steel) for an optimal distribution of the primary air coming from the air conditioner and the re-circulated one is coming from the ceiling.