Cesar Millan, the acclaimed dog behavior expert, has cared for and rehabilitated dogs for most of his life. Cesar's philosophy espouses that there are no bad dogs. Unruly and aggressive behaviors result from lack of proper training - people training. Cesar and his wife Ilusion realized that owners want to properly control their dogs during walks, but often lacked the necessary tools to do so. They designed The Illusion Dog Training Collar to assist owners in achieving maximum control during walks. It is sized for small to large breeds. The small collar is for dog's with a 13-15 inch measurement around the base of the neck; the medium collar is for 16-19 inch measurements around the base of the neck; and the large collar is for dog's with 20-23 inch measurements around the base of the neck. Note: THIS COLLAR COMES IN BLACK.