The Splitter can be connected to mobile phones/tablets/PCs/laptops and can output sound to 2 speakers/2 headphones/1+1. It can also be plugged into a receiver from the back and output sound to speakers and headphones. Finally, it can be connected behind the speakers and you can have two audio sources, for example PC/mobile/receiver or two receivers, or even connect two PCs together by connecting two male-to-male jacks from the sources to the splitter and of course plugging it into the aux port or RCA port (with a second splitter from RCA to female jack that will be connected to the source and with this splitter here). And not to forget, with a jack/RCA adapter - jack/jack adapter, you can connect another splitter to one port and you can output sound to 3 devices and have sound in the speakers or 3 headphones - 2+1 (speaker + headphones) in one device.
Note: The sound is low when all devices are open, regardless of whether one is closed. The sound comes back to normal as soon as you close it. It's not that tragic, you just need to adjust the volume when all devices are open, whether it's from the speakers or the devices... All splitters of this type work like this!

OK, it does its job, just be careful it does not contain resistors inside. It is not a passive mixer