Earpads

They are good, comfortable and fit on my HD 560S

Perfec fit for HD 598SR

I don't know why but my hd 560s has bass again after installing these new ear pads. The bass disappeared from my 18 month old, heavily used 560s' and installing new ear pads fixed it.

felt too firm at first but softened after few days

As you can read from the title I bought these pads as replacements for the old ones in my Seinheiser HD598SR. Even though these pads are meant for the HD559, they are perfectly compatible with other models, including HD598SR.
If you wonder about which other models, you could have a look at https://www.audiosanctuary.co.uk/sennheiser-replacement-earpads-hd559-hd515-hd518-hd555-hd560s-hd595.html. As you can understand, the pads may match more models.
These pads are pretty firm but after a few days of testing, I could not find any issue with them. They are comfortable and firm enough not to hurt your ears.
Very recommended.