Dog Brite EL Lighted Waterproof High Visibility Dog Collar Uses electroluminescent (EL) technology to provide a consistent glow that keeps your pet visible at night up to 1000 feet away Completely waterproof and submersible up to two feet Togglable steady and flashing light modes Requires only two AAA batteries for 70 hours of flashing light Lightweight, sturdy, and flexible. One size fits all necks 10 to 21.