Just got an email, looks like it's not yet live on the site. I believe it is good for the week, since the email said "cyber week." See attached pic.
edit: even sweeter with 14.7% cashback from TCB and 2 free pillows with code "blackfriday"
edit 2: code "blackfriday" expired. But "RizDeals10" takes 10% off, making the mattress $360. 14% cashback would make it about $310.
Tulo is Wirecutter's top foam mattress under $1k