Quick update on my Aftershokz Xtrainerz, you want music while swimming? Buy a pair, they are blooming marvelous in the pool, sound quality is great although a few of my currently loaded tracks can have a little too much bass, that could be the music more than anything though as most stuff is great. Battery life is awesome, fit is awesome, they stay on and you hardly notice them, even when I occasionally knock them with an arm during recovery they don't move and that's without a swim cap. Plenty of room for a lot of music and compared to my previous Sony NW-WS623, well, there is just no comparison, they are in a different league altogether. My only minor niggles having had them for a few months now are the aforementioned silly short cable on the charger and the slight annoyance of shuffle mode being so random it will occasionally play the same track multiple times rather than going through the entire library and then starting again, but I think this is quite common these days sadly. Massive thumbs up from me, definite recommendation 
I've just cancelled my local pool session which was fully booked and would have been just too busy for my liking, the pool 15 mins up the road is only at 30% capacity including my booking so should be a lot better.
