Medium M, width 2cm, neck circumference 37-50cm; The collar is not elastic, be sure to leave only 2 fingers between the collar and the dog’s neck. The dog collar shown in the first photo is sold separately; the matching leash is sold separately for the perfect look. A vibrant color combination of fuchsia and black. Available in a variety of sizes to suit all breeds! The ring is made of environmentally friendly plastic. The metal D-ring is chrome plated to increase product life. Photo shows size M - medium.