Input: 3.5MM for headphones or earphones Output 1: 3.5MM for headphone jack on computer/laptop Output 2: 3MM for microphone jack on computer/laptop Connect stereo headphones and microphone to both your computer's audio port and microphone port. Compatible with laptops, cell phones, desktop computers and other devices via a 3.5MM audio jack Clear sound quality, shielded design, shielding anti-interference, presenting a better sound quality effect, the Better sound quality with less loss One can be used for microphone input connection and the other for connecting external (output) speakers. Warm Tip: To ensure proper hardware detection, we recommend plugging your external headphones into the adapter before connecting the adapter to your computer or mobile device. Inside the box Headphone microphone audio splitter