The Beyerdynamic headband is well built, has a nice look and it's easy to change. I use it on a HD-660 and fits perfectly: just apply it over the metallic arc and push the four automatic buttons. While doing this, it is important pay attention to not damage the tiny wire that connects the two loudspeakers.
I usually change the headband to clean it without taking my headphones "out of order", but it is generally good to see that with a few euros it is effortlessly possible to prolong the life of the headphones: this is a feature that should be taken into account when choosing a product intended to be used many hours every day.
The headband I received has a tiny hole on the inside part, but I believe that this is not a defect: the hole seems to have been made intentionally to make the air flow out easily when the headband is compressed.