These are custom made air scrubbers running a total of 4,000cfm. With a Dual HEPA filtration system and dual out put filtration, the air scrubber filters and circulates the air leaving no traces of Crystallin Silica dust to settle on the surfaces. Use this machine while your guys are working and help eliminate the chance of them developing lung cancer from all the construction dust they breath in every day. One machine is recommended for a one story building 4,000 sq ft or less for best results. After one day of using this air scrubber on the job site you will want one on every job site. You can also order them with an ionizer inside as well.