Centrifugal blowers develop high pressure-to-volume performance at low rotational speeds for quiet cooling of tightly packaged electronic equipment under severe environmental conditions in airborne, ground based, and shipboard applications. Simplex blowers have 1 squirrel cage impeller wheel while Duplex blowers have 2 squirrel cage impeller wheels mounted on a common shaft - both are available for either clockwise or counterclockwise rotation. Duplex blowers simplify ductwork and allow greater volume performance in tight locations. As with all squirrel cage blowers, air enters axially and exits tangentially, making a 90 degree turn. All models are built to applicable military specifications.