Rhino Thermo controllersRhino Silent DAY + Night Controller 5 Speed This controller adjusts fans to run at different speed during lights on and lights off periods and off course runs them silently, something a lot of controlers on the market do not do, Thats not all through it powers an oscillatiing fan when the lights are on and a heater when the lights are off. Silently controls both intake and exhaust fans, allowing negtive pressure to be perfectly maintained. available