MaxxAir Vent Corporation’s home page features details on the Turbo/Maxx, an RV fan that provides all the benefits of a vent cover and a fan, even when it rains.
Photo Credit: MaxxAir Vent Corporation
Removing musty air, smoke and cooking odors, while preventing heat build-up, the Turbo/Maxx offers maximum ventilation with its 12″ diameter, 10-blade fan. The Turbo/Maxx features hinge-opening mounting brackets for easy access, cleaning and service. Simple to install, it attaches directly to an existing 14″ x 14″ standard roof vent, so there’s no need to remove the existing vent.
Source: MaxxAir Vent Corporation