Numerous reasons why avid canine handler & professional trainers both utilize these collars. Utilize proper steps for safety to both trainer and canine.  2.5 mm thickness and length is 17”. Chrome Plated with steel Chain Collar and toggle. Fits dogs with a larger head. Designed for a lifetime.  Built for obedience training and behavior correction. Measure largest part of dog’s head then add 2” s. Over size is measured from ring to ring on chain portion area only, see description in photos. YOU WILL RECEIVE A BONUS SLEEK WALKING TRAINING CHOKER COLLAR, 22”.