With multiple size Pet Bed Warmers available, it's now possible to add heat to most indoor pet beds. It slides into any zippered dog or cat bed and is recommended for beds with at least ½ inch of padding between the warmer and bed surface. Simply plug it in and the warmer will generate a subtle, comfortable heat that any pet is sure to enjoy. Please Note: This is a Pet Bed Warmer, it should only be used inside of a pet's bed and should never come in direct contact with your pet.