[mdotdub]

I suspect they're referring to this Amazon Renewed listing for the 660s2 for $399 with Prime shipping (not an affiliate link, just a copy/paste).
90 day return window according to the listing. If you're okay buying refurbished this is an option.

 

[Blueshound24]

I believe you are looking at "used like new"
Please send link.
Thx

Oops, my bad. I totally missed that. It is renewed.

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[mdotdub]

fwiw, I bought a pair of these renewed and they looked brand new. Pads were perfect, cords were bundled and wrapped as if they were done at the factory, carrying case was perfect and the headphones were spotless and had that clamping force you'd expect from a new set of 660s2's. It's been ~30 days and they're great. I liked having the 90 day return period and saving $200. For me, the risk was very low to get these and check them out.