I've been worried about summer in the southwest with our corgi, since his coat is pretty thick and he has been getting warm quickly as the weather has been warming up. He wore the Swamp Cooler Vest for the first time on a walk today, and was panting much less than the usually does. The vest stayed cool to the touch, and his skin and fur was also much cooler underneath it. It's long and has good coverage on the side, so it also reflects more sun. It held moisture well through a 4 mile walk. I initially got an XS as that is the size he wears in the Flagline harness, but the neck was a bit too tight and does not have any adjustment. The S was a bit too large in the chest, but I made a minor modification to the chest portion to shorten it and it fits well now. I almost wish this had a real harness integrated, but I see the utility of the lighter/simpler design that can be used with a collar or over a harness if necessary.