A newer packaging version of the classic Tuna and Chicken ready-to-eat salads offered by BumbleBee®. Each package weighs in at 3.5-ounces. The older version came in a plastic clam shell package, this version is packed in stiff paper. Find inside a small can of meat/fish with an easy pull back foil lid, a spoon and a package of crackers.
The box protects the items for pack travel. The chicken has more protein I noted, but both make an easy big snack.
Find them in the canned meat aisle, often next to the canned tuna. I have seen these at nearly all grocery chains, big box stores and C-Stores as well on the way to trailheads.