The VSC-DNe is designed to gradually increase or decrease the speed of centrifugal fans depending on the day or night temperature set-points. The Variable Fan Speed Controller enables you to determine precise temperature levels to achieve within your growing environment by way of proper ventilation. The temperature differential switch can be set at 3°, 5°, or 7°F and comes complete with a 12’ probe. The day and night temperature knobs can be set between 50°F and 100°F independently. The built in photocell will automatically sense day or night and adjust the speed of your fan accordingly. The VSC-DNe is rated for 6 amps @ 120 volt. 5 year no hassle warranty.