Blinky Balls are motion activated, brilliantly illuminated balls that start flashing with just a slight touch from your cat. Each flash cycle lasts for 3 seconds, and then shuts off automatically. So, when the sun goes down, it's Blinky Ball time! Made of rugged, non-toxic, brilliant red plastic, and comes with replaceable batteries. Great for cats and small dogs. Small ball is approximately 2" in diameter.