Thermo Kitty Sill. We incorporated advanced engineering for strength and ease of assembly, with an attractive oval design. Its dual thermostat heating unit is buried deep within super-soft orthopedic foam and is removable for year round comfort. The heater is pre-set to keep the sleeping surface 12 to 15 degrees above ambient air temperature and warms to a pet pleasing 102 degrees with the kitty on it. No tools are necessary for installation when using the provided Velcro fasteners. We also include screws for a more permanent attachment.