Kool Collar Stop Sign Red Large (24"30 1/2") Keep your pet cool, safe comfortable... How it works: Melting ice acts as artificial perspiration. What it does: Helps prevent heatstroke heatrelated health problems. When Where to use: Use indoors with KoolTube yearround and outdoors with ice when warm or active. Kool Collar is an extremely effective, unique dog cooling product. The Kool Collar is a must for inside, active, or dogs at risk for heat exhaustion or heat stroke. It is patented and very different from every other dog collar on the market. We use melting ice to act as sweat on your dog. It's easy, durable and extremely effective. Size: Large (24"30") Washable, reusable economical. Nontoxic. Vet recommended.