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 light weight, durable collar houses a flexible, light transmitting polymer core that illumninates when the collar is turned on. A reflective stripe adds additional 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. Replacement battery included. Large: 18" - 27".