It consists of only one unit that you should place where it would be most likely for an intruder to trespass. The unit detects movement within 20 feet long by 90 degrees wide. Plenty of coverage for such an affordable unit!
You can set this affordable Motion Activated Alarm with Auto Dialer to use a silent alarm or a 125dB sound. It also has the feature of sending a pre-recorded message by phone thru an auto dialer, to 3 different phone numbers! Such as the police, a neighbor, you, or any other person you might feel fit to be notified. On the pre-recorded message, you should probably mention your home or business address, your name and that an intruder has been detected on your property!
This unit with auto dialer is not only affordable, but simple to install, a no brainer to use, arms and disarms using a keypad and you can even set your own security code! It also allows for small delays in entering and leaving your home or business. It won’t set off immediately, giving you time to walk out when you set the unit for leaving your place and time for when you come back inside to turn the unit off. The unit only measures 6 1/2" x 2 1/2" x 1 5/8" and requires four AAA batteries, not included.