Doog's Stylish, Lightweight Collars Are Made From Quick Dry, Water Friendly Neoprene So Are Great For Dogs With Sensitive Skin And Hot Spots. The Neoprene Material Draws Moisture Away From The Skin. Bonus: Comes With A Silver Doggie Id Tag To Engrave Your Pet's Contact Details (Excludes X Small Size). Measure Your Dog Neck To Ensure Correct Size. XSmall | 4"-10" Length | 0.4" Wide, Small | 9"-13" Length | 0.7" Wide, Medium | 12"-18" Length | 0.9" Wide, Large | 16"-24" Length | 1.3" Wide.