These alarms alert you to movement in your home or business for security in which you can feel confident. Keychain remotes allow you to turn the alarms off swiftly without having to approach the units. Includes motion sensor, wall mounting bracket and 2 keychain remotes. Audible alarm goes off when anyone walks by—good for doorways and hallways. Sensor requires 4 AA batteries (not included), each remote requires 3 AG13 batteries (included). Sensor measures 3-1/4" x 4-3/4" x 1-3/8". Clamshell.