Professional Amplifier Audio Transmitter with Noise Cancelling Headphone Set 1. Plug type: straight plug 2. Headphone output audio source: PCHifiTVDVDCD 3. Whether wireless: wireless transmitter 4. Uses: family party, large stage party, square dance, fitness, yoga, conference, travel, broadcasting, cinema, etc. 5. Plug diameter: 3.5mm 6. Plug: 3.5mm 7. Wire length: 3m 8. Horn diameter: 40mm 9. Sensitivity: 10dB 10. Frequency response range: 20-20000Hz 11. Distortion rate: less than 1% 12. Impedance: 32?? 13. Signal-to-noise ratio 75dB 14. Distortion rate: <1% 15. Frequency response: 30-20,000Hz 16. Transmitter power supply: 420MAH built-in environmentally friendly lithium battery, 9V1A adapter power supply 17. Headphones must be connected to the transmitter for use 18. Countless headphones can be connected to one transmitter at the same time. The transmitter has 3 channels, and users can choose their favorite music as they like.