NexgenCover 3.5mm 4-Pin to 2x 3-Pin 3.5mm Headset Splitter Adapter - M/F This adapter is not a headphone splitter/Y-cable. It cannot be used to split the audio output to two separate sets of headphones or speakers. Some laptops and mobile devices will not work with all external microphones. This is typically caused by an impedance mismatch between the microphone and the device. This is due to hardware incompatibility and is not a limitation of the product. To ensure proper hardware detection, we recommend that the external headset be plugged into the adapter first, before the adapter is connected to the computer or mobile device. Turns a 3.5mm audio output port into two distinct ports - one 3.5mm headphone jack and one 3.5mm microphone port It allows you to connect a microphone as well as external speakers.