I don't really like Focal or Sennheiser pads either but at least they're consistent with their choice.
- on the left is Hifiman standard ring pad for he400i he6se he400se sundara etc.
- middle is an egg shape but you can use standard pads and it's fine. for deva 5xx r7 r9
- on the right is just for sundara closed
They also have the teardrop style pads for arya/he1000 but they're fine. But both Susvara and HE-R10 use their specific pads installation too for no reason.
tbh I reach to some of the chinese pads factory if thay will do sundara closed pads? They won't.
Also, their guide videos on how to change pads make it look "easy", which is how they describe it, but it's ALWAYS a nightmare to do so without destroying/warping/practically ruining the pad recepticle
By far the worst mounting mechanism in the industry.
DT1990 Pro was also a bit of a struggle the first time, but there was no way to destroy them. You just had to struggle for 2-3 minutes per Pad. He-1000 Pads have snapped the first time I took them off and I tried to be as gentle as possible.