Lightweight cabinet with sturdy aluminium frame and metal locking casters. A metal mesh protects the filter area. The yellow light warns of a clogged filter, the red light warns of filter leaks. A large filter area in combination with pre-separation give long operation time with high efficiency. A pre-filter made of pleated polyester catches the larger dust fractions before the air enters the individually tested HEPA H13 filter ensuring 99.99% efficiency at 0.3 microns.