Downtown Pet Supply New Glow in The Dark Dog Collar, Strong TPU Safety Collar, Suitable for Dogs or Cats SAFETY - Your pet's safety is top priority, so get them this glow in the dark collar for ultimate visibility COMFORT - Made of comfortable yet weather-resistant, durable TPU material. ECO-FRIENDLY - Never use Batteries. Save money and contribute to leaving a smaller carbon footprint. CONVENIENT - Simply leave the collar in natural sun light for ~30 minutes and it will emit a bright glow for 2 hours in the dark DETAILS: Medium Adjusts 14"-18"