These came with are frozen food delivery.
Gel-filled bags which you freeze and use to keep things cold.
8 of them.
About 4" x 5 inches (see photo - tennis ball for scale).
The delivery note says the gel is non-toxic and can be disposed of down a domestic sink when not needed.
Reusable freezer/ice blocks/bags (Comiston EH10)
This offer has been gifted to someone and is no longer available.