This is the standard collar for dogs. It has a buckle or plastic snap ("quick-release") closure and a ring for attaching identification tags. A flat collar should fit comfortably tight on your dog's neck. It should not be so tight as to choke your dog nor so loose that he can slip out of it. The rule of thumb says you should be able to get two fingers underneath the collar. Small fits 14"-17" necks. Collar is 3/4" in width.