The Green Pet Shop Cool Pet Pad is a pressure-activated gel mat: it cools on contact without electricity, water, or a freezer. Large is sized around a 35×23.6" footprint for dogs roughly in the 46–80 lb band — size up for bigger breeds.
Use it indoors or in shade on hard floors, in crates, or layered on top of an orthopedic couch. Do not leave it in direct sun or a hot car — the gel absorbs ambient heat and stops helping.
It is a cooling surface, not a thick mattress. Pair with a supportive bed when joints need foam.