This type has 4 aluminium blades riveted to a zinc plated steel spider. Diameters range from 200mm (8″) to 726mm (30″) with pitch angles from 16 to 40 degrees in 1 degree increments. The performance in this group varies from 250 – 30,000m3/h. Fans can be either clockwise or counter clockwise rotation with hub bore to suit choice of motor.