This light-up collar can flash brightly when turned on and is the best way to keep your dog's presence clear and obvious, from dusk till dawn! Visible up to 800 Feet in the dark, this collar keeps your dog safely visible to you, to cars, to other people during any late-day or early morning outing. The hidden power pack with handy on/off switch comes pre-installed with replaceable batteries that can last up to 150 hours. This collar is weather-resistant, shock-resistant and lightweight, simply the best way to solve every night-loving dog owner's problem. Please note this collar is not designed for tie-outs. The HYD L.E.D. collar uses 3V CR-2032 model lithium batteries (replacement batteries sold separately). Please measure your dog's neck girth prior to purchase to avoid ordering the wrong size. Please visit our "Sizing Guide" store page for intructions on how to measure your pet. The breed recommendation is for reference only.