The B-Wheel backward curved impeller has a seven-blade design (instead of the standard eight) in which the blade diameter is smaller than the outside diameter of the cover and support plate, which permits it to act as a rotating outlet diffuser. This wheel geometry provides for impeller efficiencies up to 78 percent, according to the company, while reducing noise by up to 3 dBA. It also increases airflow compared to standard impellers operating at the same speed. B-Wheel impellers, which offer all-aluminum construction and robot-assisted welding, are suitable for hygienic or outdoor applications without additional finishing or surface treatment. Sizes include 250, 280, 315, 355, 400, 450, 500, 560 and 630 mm.