Milesight - 4 * 2700mAh ER14505 Li-SOCl2 Replaceable Batteries Battery Life (25°C): Over 15 Years (Twice Daily Location Updates) Over 8 Years (Tenth Daily Location Updates) Over 4 Years (Hourly Location Updates) Equipped with High-accurate GNSS Positioning and Cooperate with Wi-Fi Positioning Built-in 3-axis Accelerometer Sensor to Monitor Device Tilt Status and Movement Equipped with NTC Temperature Sensor Enabling Environmental Detection NFC Enabled IP67 and IK09 Rated