They are earbuds, but they are amazing. They don't noise cancel, they noise isloate. I wear them in NYC, and whether it's a loud subway, a bus, or a jackhammer, I can keep the volume way low, and still hear the music. It's also great for your long term hearing health since you will keep the volume way low. Before I got them my iPod was at 75% volume. With them, anything over 25% is too loud. Perfect for mowing the lawn, though.
There is one con with these and that is they are fragile. The buds themselves will never have a problem, it's the cord and TRS conenctor. They will break at some point, but Etymotic is very good about giving you an RMA repair/replacement even after warranty is expired. I got tired of that, though, and I soldered on my own connector that was far more durable.