Forms a complete circle with a double slider for adjustment. Cinch down and it stays until you need to adjust it later. Recommended for active dogs on chains or towlines. We use 1" webbing and a 1 1/2" ring which makes the collar easy to find when wearing gloves or mittens and great for active dogs. Small size works for sending puppies to new homes, medium fits 10 - 16" and most sled dogs up to about 50 pounds, large fits 14 - 21" and 45 - 90 pounds.