And you apply this ring on the outside of the pad, just to force it to seal?
I was looking for some oval too, having this idea that if my pads are 800mm round I can find a 70mm + 90mm oval and when the 70mm was stretched the 90 would contract.
But all ovals I find are super big, things like 90 x 110 (like the HM5).
I have started writing questions in Amazon, you know, you can ask to the owners. Asking them to measure the pads
It worked but I did not find anything.
Only the Kicker Cush and maybe maybe the Skullcandy...
Yes. Once the pad is tucked into the groove that runs around the outside of the cup, the o-ring is pulled tight right into that groove, and wedges the earpad up against the edge of the groove nice and snug.
I would look to see whether pads meant for the Sony MDR-V6 or 7506 (or the clones thereof) might have dimensions you can use. Something like this, that's marketed as extra deep, would perhaps be okay. But you might want to buy a cheap, cheap pair that's meant to fit 7506s, try them out with a rubber band or o-ring solution to see if the sealing works, and THEN get something more costly.