Dogs in Play Multi-Function LED Lighted Dog Collar - Extra Large Collar (18-26" L, 1" W) XL collars: 18" - 26" long, 1" wide Correct Collar Size: The sizes listed above indicate the maximum size with the buckle fastened. Measure your pet's neck before ordering. You may wish to add 1" - 2" to the measurement for your dog's comfort. Don't forget to buy a matching leash!