Acoustic casing covered with sound absorbing material with anticorrosive finish in polyester resin polymerised at 190?, after degreasing with phosphate-free nanotechnology treatment. Standard flanged inlet and outlet to aid in duct installation. G4 + F6, F6 + F8 and F7 + F9 filters, according to model. Easy access inspection and cleaning cover. Galvanized sheet steel casing. Backward-curved turbine, except models 125 and 150, which have multi-blade impellers. Supplied with four mounting brackets, to make installation easier. Class F motors with external rotor, ball bearings, IP-54 protection, and built-in thermal protector, 230V single-phase. -50/60Hz. Adjustable with a maximum temperature of air for transport +50?.