1. GSM frequency compatibility: three frequency bands (850MHz, 900MHz, 1800MHz, 1900MHz) 2. Microphone range: 5-7 meters radius 3. Power supply: built-in 300 mAh rechargeable lithium-ion battery 4. Turn on the voice control function, and the expected continuous working time is 5-8 days 5. Positioning only functionality is expected to last for 16-21 days 6. When it detects sound, it will call your mobile phone 7. The built-in microphone has a working radius of up to 7 meters, so no matter where you want to set it up 8. Allow audio devices to call you when they hear people talking
