SunGlo Reflective collars are brilliant! They reflect brilliantly when a car or flashlight hits the collar. These collars are great for those of you that run with your dog late in the day or to help find your dog when they are trying to hide in the backyard. All Leather Brothers collars are measured in inches from end to end. The 16 and 18" collars are 3/4" wide and the 19, 21, 23 and 25" collars are 1" wide... all in a variety of colors! When purchasing one of these collars, purchase 2-3" more than the actual neck circumference of your dog.