They are Stereo into the transmitter, then it sums the stereo input into mono and the receivers are Mono feeding Left and Right the exact same signal. The packaging comes with an alcohol swab and the back pieces in their own individual wrapping. Aber die schwarze Sohle ist so hart, dass ich nicht damit laufen konnte und beim Anprobieren nur stolperte. I first order a size Medium for my daughter who normally wears size 10-11. People are often delighted to get a sticker. Extremely happy with this. Too weak and the high and low separation at high volume is too obvious. The characteristic of the sound is slightly geared towards the low end, typical of BT speakers, with crisp bass without buzzing. )All three of the source options work great, although it can be a little finicky and get confused when you try to switch from one to another (although maybe that?s me still getting the hang of it). Having to constantly mash your wired earbuds in your ears every 10 seconds while exercising to keep them from falling out.