They are a crucial part of home safety. They are typically required to be installed inside each bedroom, outside each sleeping area and on every level of the home, including the basement. On levels without bedrooms most states recommend installing alarms in the living room (or den or family room) or near the stairway to the upper level, or in both locations. This may even be required if your home does not burn fossil fuels. Be safe and purchase a Carbon Monoxide detector from amazon. They are relatively cheap and can save a life. Not to mention, these may hold up the sales process if they are not properly in place.