The side covers are made from rigid polyurethane forming in combination with zinc coated profiles on the top and the bottom. This design provides the maximum space for the filter media pack and obtains an extremely high mechanical strength. The fibreglass media pleated in ‘Minipleat shape’ forms one continuous media and is cast in V-shape technology directly into the frame-sealant material. This design gives an absolutely tight media-frame connection in correlation to a highly active filter surface with a minimal pressure drop. The filters are supplied with a flat flange for a secure seal between the filter and each standard holding frame.