Bluetooth Wireless Retro Microphone External Mobile Phone Handset 1. Function: Supports Bluetooth 5.0, hands-free calling (HFP v1.5), and headset profile (HSP v1.1) 2. Working voltage: DC 4V 3. Battery capacity: 200 mAh 4. Charging time: Approximately 4 hours 5. Talk time: Approximately 12 hours 6. Charger input: DC 5V, 300 mA 7. Operating frequency: 2404–2479 MHz 8. Communication range: Up to 10 meters (unobstructed) How to Use: 1. Power on: Press and hold the function button until both blue and red lights flash. 2. Bluetooth pairing: Enable Bluetooth on your phone, search for available devices, select “NFXSL”, and confirm pairing when the blue light flashes steadily. 3. Answer a call: Press the function button once when an incoming call rings. 4. End a call: Press the function button once after the call. 5. Reject a call: Press and hold the function button for two seconds, then release. 6. Redial: Double-click the function button or press and hold it for two seconds. 7. Power off: Press and hold the function button until the red light stays on. 8. Charging indicator: Red light indicates charging; blue light stays on when fully charged.