The Wireless Outdoor Siren has a 120db high output alarm. It has 3 alarm functions siren + signal light, signal light only, siren only, delay timer 0-10s. It can be used as a siren alarm with the HA-SYSTEM. The Siren can also be used as a stand-alone siren by connecting up to 8 additional sensors, HA-MOTION, HA-SENSOR, HA-MOTION-OD. To use as a stand alone system you will need to purchase an (HA-REMOTE) to arm and disarm the siren. Once one of these sensors detects motion it will sound the alarm. The siren has an automatic shut off. Every 30 seconds the alarm will turn on and off once the alarm is triggered until its reset. The siren comes with power adaptor and wall mount. It will work with 4 AAA batteries (not included).