This pet bed warmer is a 6-watt unit utilizing dual thermostats for added comfort. It can be placed inside virtually any pet bed and is easy to use. Just plug it in. It is designed to warm only when inside a pet’s bed. The pet bed warmer is intended for indoor use only. Not recommend if your dog is a persistent chewer. Three sizes: 6 inches x 20 inches (6 watt), 11 inches x 24 inches (13 watt) and 8.5 inches x 9.5 inches (4 watt). All 110 volts.