BioThane Reflective Sport Collars are perfect for walking, biking, hiking or seeing your dog in the yard after dark. Made with heavy duty industrial stitching these will last forever. Like to walk in the rain? These are water proof, odor proof and super easy to clean! The Edge Guard makes it practically impossible to separate the reflective strip from the BioThane material. The length of the BioThane Reflective Sport Collars is measured to the middle hole so you have approximately two inches of length in either direction. A 20" collar will fit 18"-22".