simpleLEASH - A No Pull Training Simple Leash and Collar Sizing: Small (13" - 16"); Medium (16" - 18.5"); Large (18.5" - 23") Safe and effective patent pending computer controlled leash endorsed by veterinarians Stops dog pulling in just one or two walks Fully adjustable collar for temperament and size of dog and owner Easy to train and use - just hold onto the leash and the computer does the rest