The Carlon Lamson & Sessons HS4313 Wireless Key Entry Contact Alarm System is an easy install, DIY alarm system for monitoring entry through a door onto your property. The included alarm mounts on your door and the included magnet mounts on the door frame, or vice versa, using the adhesive strips or screws provided. When the door is opened and the contact and the alarm are separated, the alarm sounds off. Settings for the alarm include Instant Alarm or Delayed Alarm, and an LED Intrusion Indicator flashes to let you know if unauthorized entry was requested. For added convenience, there is also a low battery indicator. The alarm operates on 2 AAA batteries (sold separately), so no hardwiring or professional installation is required.