Reddit reviews Vac-Fresh Roll Vacuum Sealer Bags, 11 inch x 50 feet, 3.5mil, Compatible with all Food Save Vacuum Sealers, 1 Roll

Also buy the plastic in bulk. I get mine on Amazon.

And always leave a sharpie next to your Foodsaver.

Edit: better deal on the 11" rolls. Two 11"x50' rolls for $17.07

I use vacuum bags off a roll; similar to this. I'd expect that I could just cut that to an appropriate length and get it to a fit a brisket, though I've not tried.

FYI you can get the bags cheaper on Amazon, I just got 50 feet of 11" for $18 here.

I love these guys: https://smile.amazon.com/gp/product/B0063HZVBC/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Awkwardsoul has good comments here, but I'll add that there are bags that are not branded Foodsaver, so they are very cheap, and just as good quality....these are all that I use.

8" wide

11" wide

If you're into marinading your ribs, you might consider getting a vacuum sealer and then buying the rolls of bags online.

Seal one end. Cut the length to what you need for your whole rib, add the ribs and the marinade, then DO NOT USE THE VACUUM. Just try and get most of the air out and seal the other end.

Now you can even freeze the rib in the marinade if you want but regardless, it's perfectly safe to go right into the fridge.

Yes, they're that cheap! :-)
This is the one I got, and these are the bags I use.

I bought a roll so you can cut whatever size you need. Hopefully the link works.

11" x 50' Roll for Vacuum Sealer Commercial Grade Vacuum Bags https://www.amazon.com/dp/B0063HZVBC?ref=yo_pop_ma_swf

These are my other thoughts:
This with this.