Overview Similar Products –> Product Description 1315 Backward Inclined Wheel 13-1/2″ Diameter 13-1/2″ Width 5-3/4″ Bore Diameter 5/8 KEYED Hole Size 9-1/4″ Radius 1-1/16″ # of Blades 15 Rated 3450 RPM Aluminum Replaces such roof-top ventilator brands as: Chelsea, Green Heck, Acorn, and Penn Vent. Backward inclined wheels are designed to pull air into the opening (hole size) and discharge on all sides. With this in mind we can often replace a CW rotations wheel with a CCW rotation wheel by simply reversing the motor rotation. Product Videos Custom Field Product Reviews