Shure SE215 Pro CL

I use it for live vocal monitoring and it does the job.

The frequency response of these in ears is awesome.
The low and the high frequencies are very clear and lets not forget the mid range sounds quite flat, witch is important for a vocalist because that's where you hear tone.

They isolate like crazy though I had a hard time removing the standard ear plugs and fitting the smallest ear plugs for my small ears.
They where clamped on so hard that I was afraid I would brake them.
Luckily that didn't happen.

Once you get used to how.....they are easy to get in.
But the cable that runs down you back keeps getting hooked at the neck of you t-shirt witch can be distracting. Solution: put the cable trough a paper clip and clamp that on you T-shirt and the cable stays in place.

After using the SE215s for just over 3 years, I think I can give a fair judgement now. They are used during running (also during rain), riding motorcycle, in the bus, at university/work, behind PC. Pretty much all imaginable scenarios.
In these scenarios I have found all other headphones I used lacking in either: sound quality, durability (especially near the jack-plug and being semi-waterproof) and/or flimsy cord.

So far the SE215s have suited me reasonably well.

What I like:
-They seat very well, only headphones that I can go running with without them falling out.
-Excellent music quality for the price and form factor.
-Reasonably waterproof due to the tight fit.
-Durable cord that isn't prone to breaking.

What I dont like:
-The connectors between the earphones and cord are very prone to wear, and non-replaceable. This is a known issue for Sure but they dont fix it. If I had the option I'd rather buy these headphones with fixed cords instead of this point of failure. For me this happened about 2 to 2.5 years after use.

The only thing holding back 5 stars for me are the connectors that are very prone to wear and dirt.