Etymotic Research 6i Isolator (ER6IB) Earphone / Headphone

Pros: See above
Cons: See above

The earphones do an extremely good job of keeping out noise, and the sound quality is fine. It does take some effort--and maybe some break-in time for the phone seals--to learn how to seat them in the ear properly. Don't give up too early.

I had to return them due to a problem with the connector. This was probably due as much to my rough treatment as their design, and in any case the phones they sent back are of a design less likely to cause trouble. (Customer service was very good.) Still, I wish they made them for heavier use, like Panasonic makes Toughbooks. Thicker wire would be a good start. I'm being extra careful not to stress the connector this time.

One other concern is that you have to be careful to keep wax out of your ears, as this can plug up the tiny hole that the phones position close to your eardrum. I understand this can also cause the filters to need replacement, although it hasn't happened to me yet.