The #1 reason for puppy fatalities is inadequate heat during the critical first 48 hours. These durable, energy-efficient heat mats are constructed of rugged ABS plastic with a steel-wrapped cord. Includes built-in thermostat at 102 Degrees F. The optional rheostat allows temperature adjustments from 100-104 Degrees F, or OFF. Accessorize your pad with the washable faux lambskin cover. A must-have for whelping boxes. Choose a size to allow room for your dog to lie off the mat if it's too warm. Caution: Never use with cedar chips or other combustible types of bedding.