I practice swimming 2 times per week (3km, 3 strokes: breaststroke, backstroke and crawl) with goggles and swimming cap. I tested several helmets and caps before choosing this one .. Very happy with this product ... I had my music in both ears throughout the year (3km each time, about 1:30). .. it often happens that the headset moves with the rhythm of the crawl and the alternation of strokes ... with this headset, I managed to put the headset without the water enters and prevents the sound arriving as was the case in all my previous helmets ... I have adapted plugs / tips "tree" because my ear canals are very close .. no problème.J'ai could plug my MP3 distance counter (Décath) adding to the cable jack. Only downside: too bad the rigid structure can not slide to fit the size of my head (it gapes a little behind ... but that does not bother during exercise ... but the ergonomics could be even better) and the cord is a bit long .. I was forced to put a little wire under my bathing cap so that it does not tickle my back for 1:30 ...