2' x 4' motorized HEPA filter modules with hazardous environment motors. Motor are rated for class 1, Group D Motors voltage is 460/3/60. Filter efficiency is 99.99% @ 0.3 microns and larger. Filter face velocity 90-100 F.P.M. Face screens to be expanded steel with white coating (standard face screen). Prefilter efficiency is 30% ASHRAE, perforated protective screen is included.