The unit design utilises a small motor coupled to a reduction gearbox to mechanically shake the filter bags clean once the integral top mounted fan set has been switched off.

The shaker motor and gearbox are located inside the filter unit and are unseen from outside. The M unit is a compact design and employs an envelope type filter bag within it with the dust collecting on the inside of the filter bag, therefore making access to the filter media available from the "clean air" side of the unit.

To give a wide variety of filter unit sizes, the M unit range is built around a modular design woth the "single bodied" unit available in a range of filter areas from 8 to 40 square metres of filter area . The range is then built up around the duplication of bodies with the largest standard unit built as one construction being the 8 bodied 256M which employs 256 square metres of filtration media.