This motion detector is both an ear piercing security alarm and a pleasant entry announcer. It can be used by stores during the day, for example, to let staff know a customer has entered and then turned into a security alarm at night. The detection area is a 90 degree view with a radius of 60 feet. Includes a removable and adjustable wall mounting bracket. The alarm measures in at 4" x 2 1/2 " x 1 1/2" and it can easily be removed from the bracket and taken with you when traveling for securing a hotel room. May be used to monitor children or the elderly inside the home. Requires three "AA" batteries that are not included.