Item No.: CH7100 A c-wire is required for all systems Heat Pump or Conventional Heating System  2 stages or more stages heating and cooling Works with two stages of heating and two stages of cooling (2H/2C) Works with Heat Only and Cool Only system  Works with Heat Pump (With or Without Aux) Works with Amazon Alexa, Google Assistant Remotely control your home comfort from your smartphone Using the free mobile app for Android and iOS devices. 4.3 inch TFT Capacitive Touchscreen Display