I received a six pack of these. They're extremely easy to install. The wires are colored and intructions walk you through how to set up. There's a back of battery for power outages. Also comes with dust coverings too. During us testing one, it alerts you with a very high pitched alarm. We have wood heat, and these provide us with security and peace of mind, giving us ample time to get out of the home, should an accident occur. I received a free product for the purpose of my review. Opinions are 100% my own.