Features: 1.One way 3G/GSM SMS alarm, DC5-15V power input, external rechargeable battery (not included) for power failure alarm. 2.The input is a switch signal. When the input port is short-circuited with the ground wire (GND), the alarm will set off an alarm. 3.Send an alarm message to the preset mobile phone, or call the set alarm number, the content of the alarm message can be set by yourself. 4.When any alarm input is triggered, an SMS alarm message will be sent to up to 6 preset mobile phones. 5.Very smart and slim GSM design box, which can be easily installed on other target system boards to add GSM alarm function. Specification: Item Type: 3G/GSM Alarm_x000D_ Material: ABS_x000D_ Power Input: DC5-15V_x000D_ Working Frequency: UMTS: 850/900/1900/2100MHz_x000D_ GSM/EDGE: 850/900/1800/1900MHz PackageList: 1 x3G/GSM Alarm 1 x Antenna 1 x Sound Alarm 1 x Manual