Well the actual driver inside should last you a lifetime, the plasticky headband on the other hand...
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Also related:
The Sennheisers branded ear pads or Brainwavz (IIRC) ear pads are a bit expensive ($20+).
You can get generic "memory" foam ones on AliExpress for $4.
It's not actually memory foam and they might send you the wrong type, and it's a tight fit (just remember to breathe !?) but they work.
BTW I actually ended up buying Sennheiser headphones after I returned the crappy ones.