The Nite Ize light up collar is the answer to every night-loving dog owner's problem: losing sight of their best buddy after sundown. Made of high quality nylon, this lightweight, durable collar houses a flexible, light-transmitting polymer core that illumninates when the collar is turned on. A reflective stripe adds additonal safety by providing passive reflectivity. Powered by a super efficient (100,000 hour) LED bulb, it's literally a brilliant way to keep your dog safely visible - to you, to other people, to cars - during any late day or early morning outing. Replacement battery included. Size small 10" - 13".