Cat Napper Window Sill Bed, 15 x 24 . This patented product from Flexi-Mat Corp meets the instinctive needs of cats to look out windows and be up off the floor for warmth and security. Adjustable to fit most sills, the Cat Napper allows you curious feline to see both outside and inside while the warm, cozy hammock design molds instantly to your cat's shape for maximum comfort. The structural plastic frame is designed to hold up to 35lbs and is so easy to assemble, that the Cat Napper can easily be moved from one window to the next.