Received these three weeks ago, wear them every few nights, and the heels are smashed down flat as a thin little board, they don’t spring back at all. Overall, theyre definitely amazing considering the price tag. They were like wearing slippers but cool and I never felt my feet get hot, sticky, sweaty, or uncomfortable. THANK YOU Birkenstock and Amazon! Others may find it outdated but then will pay a lot more for similar features. But after getting dirty thought of wash in machine and screwed it all. I wear a 10 normally (sometimes 10. I called and they didn’t seem like an eq app was something they had any interest in adding. The second I slipped this over my head one of the speaker wires ripped off. Expansive (for a closed back).