The automatic dog waterers have optional thermal covers, sold separately. The "Chiller Cover" is a 3/16 inch laminated, metalized bubble cover that reflects the sun's rays, helping keep the water container cool. Try this when it gets hot. Freeze a gallon jug of water and drop it into your critter cooler like a big ice cube, close and then cover with the chiller cover and the water in the bowl stays cool all day.
Thermal sun protection helps keep water cool, healthy and dogs happy
Dogs prefer to drink cool water so will drink more and are better hydrated
Cool water inhibits algae and bacteria growth, better for dog health
Not recommended for "chewers" unless you also get a Heavy Duty Cover to cover the Chiller Cover. The Heavy Duty Cover is tear resistant.