4 in 1 Out / 1 in 4 Out AUX 3.5Mm Stereo Audio Input Signal Source Switcher, 4-Way Switch Selector Splitter Box M41. Build in solid aluminium CNC chassis, looks nice and durable. This TENEALAY M41 is a mini size audio source input signal switch box, you can select signal and without plug/replug cables or using the music player any more.