Wireless rolling door sensor(with lithium battery)Features:Working distance: 100m (Open field)Decode: Fixed code by pinsAlarm time: 5 secondsMaterial: aluminium alloyBattery: 23A-12V battery (included,Website:http://www.home-security-life.com, useful life time 6-12 months)Indication of low batteryApplication:Mainly used for roller shutter/rolling door; also applied to other doors and windowsInstallation:Stick part A (magnetic bar) on the edge of the roller shutter/rolling door, and stick part B on the fixed frame of roller shutter/rolling doorNote: The distance of these two parts shall be less than 3-5 cm when the roller shutter/rolling door is closed.Usages:Pull out the antenna of the transmitter.When the roller shutter/rolling door is opened from the closed position, LED 1 will turn on red light for 5 seconds; the sensor will be triggered and will send alarming signal to the main unit.Indication of low battery: When the voltage of battery is less than 7.5V, LED 2 will straightly turn on red light. At this time, you must immediately change the battery.