The BTC-1a Basic Temperature Controller is designed to control fans, heaters, air conditioners and other equipment in gardens, greenhouses, grow rooms and other environments. It can operate in either cooling or heating modes. The BTC-1a features a readily visible switch to alternate between cooling and heating, making it easy for the end user to differentiate between modes. Easy-to-read dials make programming daytime and nighttime settings uncomplicated. The (3) function LEDs let users know if the controller has main power, if the controller is in operation, as well as whether the controller is sensing day or night.