Absolute filter with a mounted duct terminal

This particular type of filter is used as a terminal and it has the same attributes with the rest of the filters of H14 classification. However, due to its metal frame and its protrusion all around it, it can lay on the flanges for example on a false ceiling. At the rear side of the filter where the intake is, the flange of the box can be connected airtight with the edge of an air duct.