The Perfect Dog&trade; Command Collar&reg; Large Dog Training System Training system includes Command Collar, 4 additional quick fit links, and the 30 Minutes to the Perfect Dog DVD Instantly corrects your dog jumping up, barking, digging, chewing, and stealing food Teach your dog to lie down, stay, and wait for you Features Non-Shock, patent pending designed links that mimic a mother dog's natural corrective process Easily adjustable to fit your dog from puppy to full grown