I replaced the battery in my Gen2 A50s with this and the time between fully charged and the time I hear the first battery low warning beep has gone from 45 minutes to over 6 hours (Listening to music the whole time). I bought 6 sets and a few of them were horrible in sound quality, very tinny, echoy, and/or sound very far off. I would say these definitely run true to size. But it appeals to me perfectly in so many ways. Fits well, no complaints. Some distortion at maximum volume,, not a problem to me as that is too loud anyway. I loooove this shoe tower! cozy though if you are wearing socks lol. I bought a case made by caseling to hold the speaker and charger and this fully protects the speaker when traveling. un tres bon achat.