Construction Direct drive. Two different constructions are available: A and B. Construction A Cylindrical stack with plate square base for fixing on to a horizontal base, or fitted to suit the roof pitch. The fan is galvanized, fitted with a rain hood as protection against adverse weather conditions. Construction B Cheaper construction without square base. The impeller is made of diecast aluminium and 5 adjustable baldes (for both constructions A + B). Motor The motor is three-phase, 230/400 V, 50 Hz, V6 (other frequencies, tensions on demand). Direction of the air The specifications listed in the tables refer to construction A. As to construction B the specifications change as follows: SPECIFICATIONS - 10%; ABSORPTION + 10%; NOISE LEVEL + 3÷4 dB/A. N.B.: To protect the fiberglass hoods during transport, they are delivered disassembled.