The K&H Kitty Sill is one of the most popular designs we offer. It has an attractive oval shape, and is built for strength and ease of installation. It is offered in both a heated and un-heated design, and the heated design operates on only 6 watts. No tools are necessary for installation when using the provided Velcro® fasteners. It also includes screws for a more permanent attachment. Either way, the K&H Kitty Sill offers a sturdy, comfortable window to the world. UL and CUL listed.