I think there is a design defect in the QCII headphones. The mechanism that allows you to adjust the headphones to suit your head size / ear position is really flimsy. Six months ago the left side on mine broke and I've patched them up with electrical tape. Yesterday the right hand side did the same thing. Believe me, at $300 a set, I baby these things. But if you look at the mechanical design of the slider mechanism on each arm of the headphones, you can see how easy it is to crack the plastic when the arms are extended and you the pull the earpieces apart so that you can put them on.

Not what I was expecting for my $300. I'll be interested to see what Bose says - I can't believe I'm the only one to experience this.