Earpads for HD 500, HD 590
The earpads and foam discs on my 20+year old Sennheiser HD570 headphones were showing there age so I replaced them
I am amazed that Sennheiser still stock spares for such old (but still great sounding) headphones.
Easily replaced, they have rejuvenated my headphones. Hopefully they will last another 20 years before requiring replacement!