maxb3k,
It's a Yellow Line Rule Mechanics bag. I have three of them on my daily riders. I really like these tool rolls and the price can't be beat either. Once you snug it up they don't come loose from the saddle but are really easy to get off the saddle for a quick repair.
They are actually on sale now for $44.00 CAD. Yes, made in Canada.
Get one here:
Mechanic Edition Tool Roll | Yellow Line Rule