SE Visible at Night,PS404M Lighted Collar Medium 16 1/2 to 20 1/2 Lights Red Illumina. Improve your best friends safety day or night by making him/her ultra-visible! Flashing LED-illumination technology with high-reflect material visible in low-light up to one mile Strong, durable & comfortable 1 inch nylon-web belting, size-adjustable with secure quick-release buckle Lightweight and weather-resistant; large stainless steel D-loop for license/ID and leash 100,000 hour flashing LED have excellent battery-life; easy to replace CR2032 battery included