Functions and features: 1) Offer 4 / 8 RJ11 output ports to connect 4 / 8 sensors or display systems. 2) Offer 2 online RJ12 ports for 2 or more 4/ 8-port alarm unit using at same time to be 12/16/20/24/28/32-port central control alarm system. 3) Offer 1 external remote RJ12 port to connect various external alarm signal / siren such as ES521IR to realize long-distance remote function. 4) Metal case, LED indication function to show work condition of every defense area. 5) Can customize wifi Bluetooth reception function. 6) Built-in rechargeable lithium battery with 7 days standby time in maximum, low battery indication function. 7) Alarm will be triggered when alarm unit is detached. 8) Code modification function. 9) Offer power switch. 10) Built-in short-circuit protection function. Main parameters: 1) Size: 185 X 80 X 36mm. 2) Case: metal 3) Output port: 4 / 8 ports of RJ11 4) Alarm volume: 100DB. 5) Standby time of built-in rechargeable lithium battery: 7 days 6) Code modification function: yes. 7) Low battery indication: yes. 8) External power on / off indication: yes. 9) Power input port: DC Optional accessories: 1) Power adapter: 5V/8A. 2) AS3X series IR remote keys. 3) ES521IR external remote signal. 4) RJ-2 cable.