I got this after trying several cheaper adapters, all of which fell apart within a few days, or simply did not work in the first place. In this case I am happy to say it works exactly as it should. The cable and jack design is the same as for Grado headphones, as you'd expect, so it looks pretty good with a set of Grado headphones, but the plain black design probably won't look out of place with anything. Durability-wise I can't say yet, but since it appears to be the same as the cabling on Grado headphones I expect it to last pretty much indefinitely. The whole thing feels very secure and well constructed.
This sounds like a 5-star review, but good as it is, I don't feel the price is justified. Grado equipment is expensive in Europe anyway, even when you consider the generally high price you pay for decent audio equipment, but it's only 15cm of cable and two jacks; really, these should be included with the headphones.