We recently switched Oscar over from his puppy food to his adult food, Blue Wilderness Salmon Recipe. It's a more expensive food than his puppy formula, so we bought agiant bag of it. That way, even though it's more expensive overall, the unit price is cheaper. Since there's so much of it and Oscar's so small (even though he could probably devour it if we let him), we got one of those food sealer machines so that we could keep the rest of it fresh after opening the bag.
The machine came with a few bags.
You fill up the bag and the machine
vacuum-seals it up. Easy!