YANMAI K3 Pro Head-mounted Mic Teaching 2.4G Wireless Bluetooth Voice Amplifier System Mic 1. Professional Audio Processing: Built-in DSP anti-howling chip with noise reduction function eliminates background noise and feedback, ensuring crystal-clear audio quality for professional teaching and presentation environments. 2. Advanced Wireless Technology: Equipped with Bluetooth 5.3 version and 2.4G wireless transmission, providing stable connection up to 20 meters distance with worry-free pairing and broad compatibility. 3. High-Power Audio Output: Features 3-inch built-in magnetic speaker with 20W maximum power output and high-quality sound reproduction, ensuring your voice reaches every corner of large classrooms or outdoor spaces. 4. Extended Battery Life: Large 2500mAh lithium battery in amplifier provides over 15 hours of continuous use, while 300mAh microphone battery lasts up to 10 hours, perfect for all-day teaching sessions. 5. Fast Charging Convenience: Type-C mainstream fast charging interface improves charging speed - amplifier charges in about 3 hours, microphone in just 1.5 hours for maximum convenience. 6. Versatile Application: Perfect for teachers, tour guides, sales personnel, outdoor entertainment, morning exercises, speeches, training sessions, and religious activities requiring voice amplification. Specifications: Receiver: 1. Charging Current: DC5V-900mA 2. Charging Time: Approx. 3 hours 3. Bluetooth Version: V5.3 4. Speaker: 4Ω 5W 5. Usage Time: Over 15 hours 6. Battery Capacity: 2500mAh 7. Transmission Method: 2.4G 8. Frequency Response: 100Hz-13KHz Transmitter: 1. Charging Current: DC5V-200mA 2. Charging Time: Approx. 1.5 hours 3. Signal-to-Noise Ratio: Greater than 85dB 4. Directivity: Omnidirectional 5. Usage Time: Approx. 10 hours 6. Battery Capacity: 300mAh 7. Sensitivity: -50+3dB 8. Receiver Distance: Greater than or equal to 20M