Paolo, they fit in well enough, I havent had problems with them falling off as they fit well.

However, since it has a standard 3.5mm audio jack, you can fit any other stamdard headphones to them that you like.

BTW for clarity's sake, I'd like to mention that the actual bluetooth part of the MW600 with the controls is something you have to clip on to your clothes, like the BH-111, which is another thing you can look at.

Its been a long time since I gymmed I'm hoping to rejoin this week, I can tell you more about how well it fits during activities then.