http://www.newenoughhp.com/closeouts/lu ... k_bag.html
It wasn't a blind purchase, I went out the day that I ordered it and too tape and calipers to pull a number of measurements, then compared them to the website.
Fit is snug. So snug that considering that my legs are on either side of it, I didn't bother strapping it down. It's not so snug that it can't be removed, but with the stiff bottom, it just fits fantastically. I did use one of the straps as a safety, just in case something happened, it won't fall off. I found that an added bonus to that is that when I want to open the seat or put gas in, it slings off to the side similar to the way a helmet would hang off the hooks.
Pics:

Basic demo of how it looks on the bike from a few steps back.

Close-up shot showing fitment.

This is the hanging position for when gassing up or fully opening the seat.
They also had a smaller one for $7.50 which I'll be reworking to make a tank bag mounted GPS case, more on that later. (I think that one is still available).
Lastly, if you buy one, there's something up with their donation program right now as ModernBuddy wasn't listed. I skipped the donation and after ordering, emailed them (via replying to the order confirmation email) and requested that my donation go to ModernBuddy. I got a response the next morning saying that it'd be no problems.