Audio switch for 3.5mm (1/8") audio jacks. It can be used in two directions: 2 IN 1 OUT & 1 IN 2 OUT 2 IN 1 OUT: Connect with two audio sources (example: computer and TV), then connect with one output (example: speaker). The A/B switch pot is for selecting one of the audio sources to be routed to the output. 1 IN 2 OUT: Connect with one audio source (example: mp3), then connect with two outputs (example: headphones and speakers). The A/B switch pot is for selecting one of the outputs (2 outputs are not simultaneous). Microphone headset also compatible: This box works with any four-segment (TRRS) audio jacks, means that if you plug in headphones with a built-in microphone, the microphone will work through the switch. TRS also Compatible. Built in mini size aluminum chassis, looks nice and durable. Passive switch that does not need power supply. The most notable design highlights of this audio switcher are: Independent Ground Wire Design: When you connect two audio sources simultaneously, the ground wires of the two sources are independently separated. When switching channels, the ground wire is also switched, avoiding noise caused by a shared ground and ensuring high-fidelity audio reproduction. (This is different from other products that use a shared ground design.) Compatibility with 3-Segment and 4-Segment Headphone Jacks: This device supports the use of 3-segment (TRS) headphone jacks and is also compatible with 4-segment (TRRS) headphone jacks with microphone functionality. It can be used for audio playback and supports microphone functionality. Compact and Well-Designed: The SPRODIO audio switcher is a compact and meticulously designed 3.5mm bidirectional audio interface switcher, allowing users to conveniently switch between two audio sources/playback devices. Use Cases: Switching Between Devices: Perfect for users who need to switch between two audio sources, such as a computer and a smartphone, without frequently unplugging and re-plugging cables. High-Quality Audio: Ideal for audiophiles or professionals who require clear, low-noise audio transmission. Simplicity: Great for those who want a plug-and-play solution without complicated setups. Compatibility: The device supports both 3-segment (TRS) headphone jacks and 4-segment (TRRS) headphone jacks with microphone functionality, ensuring worry-free usage.