4-Mode LED Light-Up (Glowing, Flashing, Illuminated) Nighttime Safety Collar for Dogs - Neon Blue Size Large collar measures approx. 1 inch wide and adjusts for neck girth of 16 inch to 20 inch Bright Blue Glow! - a brilliant way to keep your dog safely visible in the dark Constructed with durable rip-stop nylon, hidden power pack with handy on/off switch and a side-release buckle allows single-handed release Constant On, Steady Glow and Continuous Flash modes to choose from - visible up to 1,000 feet in the dark Powered by long-lasting easily replaceable CR2025 lithium batteries (pre-installed)