I ordered 5 new smoke detectors for my house. They are the hardwire kind. We are having an electrician come out to install in a couple of days. My others are over 10 years old. They need to be replaced every 10 years. I know it is easy to switch them out yourself, but electricity is something I don't play around with. We decided to hurry up and get it done because Harvey is finishing up down south. Once the rain really stops, all of our contractors will quickly head down south. So we decided to hurry up and get it done.