USB external sound card - single/dual-hole can be used. Three-hole output can be used simultaneously - headset and headphones can be used simultaneously. Computer connected to microphone - live lectures/video recordings have clearer sound. Computer connected to speakers/headphones - listening to music/watching , the sound is more immersive. Stable transmission and quality - enameled copper wire core, low transmission loss, purer sound quality. Noise reduction chip filters noise - sound card chip, stable noise filtering, clearer sound quality. Note:If computer's external HUB or USB extender is connected to sound card, there be insufficient power supply and current sound. This is not a quality problem, but this wiring situation. It is not recommended to buy. Colour:Gray Material:Aluminum Alloy Package Contents: 1 * External USB Sound Card Only above package content, other products are not included. Note: Light reflection and different displays may cause color of item in picture a little different from real thing. The measurement allowed error is +/- 1-3cm.