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.
Yeah Hifiman is a bit ridiculous when it comes to pad mounting. Also I Sundara Closed is on huge discount from Hifiman store now, probably didn't sell well.
Which also explains why other companies doesn't want to make pads for it.