I bought Sony DRBT50 head phones two years back. I was really amazed by sound quality of this headphones as this was as good as wired ones plus freedom from wires. I am using them regualrly for my gym and week end hiking. This set is working perfect for last two years and I think it will go on. I use them with my Sony Ericsson W550 phone. Batteries of this set is amazing as even after two years one full charge lasts for 7 to 8 hours of play (I normally charge them once in a week). Microphone quality is not that great but I dont care about microphone as I use it primarly for listening music while working out.