RV Roof Vent Vortex II Ugrade Kit Multi-Speed Fan Fan will move 3 to 4 times more air than a normal roof vent fan. Features a 3 speed fan with 2 speed reverse flow to allow air in or out of your RV. Installs easily and fits most 14" X 14" roof vents This unit will replace the screen on your current roof vent. The only tool required is a #2 phillips screw driver