Milesight - 1 * 4000 mAh ER18505 Li-SOCl2 Replaceable Battery Battery Life: Around 4 Years (100 Triggers per Day, 25°C) High Precision PIR Sensor + Thermopile IR Temperature Sensor Ultra-low Latency Adjustable Detection Angle Optimal Desk / Seat Guidance Advanced Features: Milesight D2D Controller NFC Enabled IP30 Rated