3.5mm Jack: with 3.5mm jack for headphones. Plug and play: USB 2.0 interface, built-in 16-bit sound card, built-in ringing, no need for sound card and additional power. Music Player: Built-in DSP echoes side sound cancellation chip, can be a good music player. Clear Sound: The volume can be adjusted during the call, the microphone is muted, DSP voice processing, the voice is clear, and the SDK is open.