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The transmitter can be clipped to my shirt instead of having wires going all the way down to my pocket. When I go to the gym I would like to be able to leave my phone in my pocket while still controlling the music. It makes it less likely for the wires to get caught on something in my daily train rides also.
 
Headphones

I've been using the Pulsar 590A with Universal Bluetooth Adapter. You do not need the Universal Bluetooth adaptor with the iPhone 3Gs. It works really well giving full remote Voice Control for full stereo music and telephone calls. They are not "in ear" so a bit bulky, but they don't fall out! The adaptor is useful for bluetooth connections to and other devices, including 2G and 3G (but without voice control)
 
You say you want buds but... I can heartily recommend the Sony DR-BT21G. I go running with mine on, like, outside running on uneven ground, and they stay on firmly the whole way around, they stay in way better than any buds or plugs I've ever used.

Of course, maybe you've never had a problem with buds or plugs falling out - everyone's ears are different.
 
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