Now for the NEST Protect. This is another tool in the wireless home automation tool box. The NEST Protect is a smoke detector and CO (carbon monoxide) detector. It communicates with the NEST thermostat and if there is a smoke or CO event, the Protect can be set to tell the thermostat to shut down the furnace. And as with the thermostat, the Protect can be monitored from the phone app. The unit goes through a self check daily. It is available in two styles - battery and wired, and comes in a black or white finish. The NEST Protect will also communicate with other NEST Protects in the house if you have more than one unit. So, for example, if you have a Protect on each level of your home and there is smoke in the basement, the Protect on the second floor would let you know. The Protect connects to your home network only on 2.4 GHz WiFi.