The Fling-ama-String Cat Toy hangs on any standard door knob. It is battery-operated and can run for hours. A long string is sewn to a soft, flat elastic "conveyor belt" which constantly rotates to bring the string out and then back in. Even if the string is caught, the string will automatically begin to rotate again after it has been released! The toy has 2 speeds to satisfy the frisky or faint feline. The Fling-ama-String was a "Best New Products Showcase winner" at the Global Pet Expo. Takes three AA batteries (not included).