Calhoun is right. I should have specified that these "6500 Series Vinyl
Windows" are the installed windows, which are clearly much better than
those AC ones that are stocked in the stores.

Now the installer said that these were Simonton, but that since they
were rebranded by Home Depot, they weren't allowed to advertise that.
But some people tell me that these are a lower grade Simonton
contractor windows, while others say that they are something like
Simonton 5100s or so.

They are fine windows, and I'm happy with them, but before I get more
directly from Simonton, I'd kinda like to know what my first batch was.
Simonton is obviously not going to help me figure it out, and Home
Depot is probably contractually barred from doing so.