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 degree to 15 degree above ambient air temperature and warms to your kitties natural body temperature when they lie on it. No tools are necessary for installation when using the provided Velcro fasteners. We also include screws for a more permanent attachment.