Simple and affordable way to keep your pet comfortable indoors or out. Built in thermostat, tough, easy to care for exterior. Provides safe radiant heat that will match your pets body temperature range. Rheostat (separate purchase) must be used for temperature control, allows full range of adjustment from full heat to off. Adjusts to correct temperature for puppies or sick animals. Covers are sold separately. Covers are open mesh washable faux lambskin that is designed to let the heat radiate properly. Available in 16.5 X 22.5 or 22.5 x 28 inches.