Martingale Collar for Dogs, Biothane, Stainless Steel Hardware, No Pull, Made in The USA, Professional Grade, Medium, TealSIZE Medium (15" 19") The Perfect Martingale Collar for Dogs in Training or Everyday Life. We have different sizes and colors for all dogs. This is one of two collars I use in my training practice for my clients. We are proud to say that many professional trainers handlers, groups, and owners use our training equipment for their dogs and puppies. Our Biothane Martingale Collar is Safer and Sturdier than other collars in the industry as we use the hole