This External Siren is an accessory to be used only with Streetwise Motion Alarm with Keypad (Item MAK20) to create an ultra loud security system. If an intruder sets off the MAK20 this External Siren will also sound. The deafening sound created by combining two 130 dB alarms will scare away any intruder and alert the occupants. Can be mounted outdoors to summon help from neighbors and police. Easy to install. Includes 50 ft. of wire and plugs directly into the MAK20. Tamper proof- cutting or disconnecting the wire will set off the alarm. Requires four “AA" batteries.