They don't actually have L/R Stereo as advertised, both earphones just play the right channel exclusively. The button on the earphones is hard to press while wearing them, without accidentally shoving the earphone halfway down your ear canal. There's no way to turn down the master volume, so if you're wearing them when they pair/link/do anything then you're going to be deafened by it yelling “LINK CONNECTED” at full volume. There's a slight but noticeable audio lag if you're watching a video.
But they're cheap and the battery seems to last ok. They work fine for the gym or wherever.