The device works with all UL-listed smoke and carbon monoxide alarms manufactured after 1999. If you already have Wi-Fi, the device does not require you to purchase any additional products. However, fire experts recommend replacing all smoke alarms after 10 years of use as older models may not work effectively. If your smoke alarms were installed before 2005, it is time for them to be replaced. Kidde CO alarms contain an end-of-life warning that will sound after 7 or 10 years, depending on their date of manufacture.