Comfort

The Ultimate Ears was at first a bit hard getting used to, but after using them for a couple of hours in a row I started to feel comfortable. The Ultimate Ears Super.fi 3 Studio is by far one of the most comfortable in-ear-monitors I have ever tried because there is no need to insert them as far into the ear canal as with most conventional in-ear-monitors. This means less irritation and an easier fit. Another positive aspect of the in-ears is that they only weigh about .5 oz which is so light that you barely feel them in your ear.

Durability

I have to admit that in-ear-monitors aren't the most durable audio devices around, however, the Ultimate Ears feel quite sturdy and the fact that you can change the cable without having to dismantle the earphones is a nice touch. The monitors themselves are made from two pieces of high quality plastic. Even if you squeeze them firmly together the plastic doesn't give way so the basic construction is quite well made. The only obvious durability problem with them besides the breaking of the cord and then ruining the housing is shock. I don't think that the armature insides will last very long if they are subject to strong G-forces, but again that goes for all headphones on the market today. Of course this does not mean that using them while jogging will break them, any normal usage scenario I can think of will not harm those monitors.