The only people with symmetric ears (that we're aware of) are certain robots, and they're not really people and they probably don't listen to music.  Regular people like us (we're assuming you're a lot like us, ear-wise) have asymmetric ears, so an asymmetric bud like Asym (pronounced Ay-Sim) fits like nobody's business (an idiom, meaning great).  Its flush fit and wrapped cable position (the cable runs over the top of your ear, man) means you can run on the treadmill (what are you running from?) or do your Flashdance dance (without water of course...they're not waterproof), and they'll stay put.  Asym also fits perfectly under beanies and helmets (for those doing the really sketchy stuff).