I bought the ones pictured and the headband detaches and works perfectly with Koss KSC. There are a couple of very similar looking products out there on ebay and amazon marketplace which are not quite identical so no guarantee that the band will detach. Check the images very carefully and if the headband attachment point isn't absolutely identical to the one in that amazon pic then it's not what you want. If you buy something which isn't exactly as pictured then you are entitled to a refund. In my experience ebay UK are actually really good in enforcing this. If you buy something which
is exactly as pictured and described but isn't what you assumed it would be then that is probably money gone.
Just in case the amazon product disappears or changes, here's a pic of the headphone with useful band:
and a very similar one which is probably not useful:
You can see the in the second one that the outward facing side of the metal band is enclosed in the slider instead of being exposed, that the short angled plastic section at the bottom of the band is different and that the circular attachment point on the earpad is a bit larger.