EBayPure Dog K9 head collars are simple and effective aid to help you train your dog without force. Just put the head collar on your dog and you will be able to easily guide your dog during training. If your dog pulls sharply forward, the slip ring under the jaw tightens the collar so that your dog's jaws are gently forced to close. As soon as your dog stops pulling on the lead, the bands loosen and your dog can open their mouth again. Training aid for dogs Gently train and control your dog without force Unique muzzling action: If your dog pulls on the lead, the straps with muzzle their mouth and only relax when your dog stops pulling Comfortable: fully adjustable, padded. Nose band Stops pulling Quick release clip Reflective trim on the noseband: for higher visibility Training manual included with helpful hints  Size measurement's 2.5Cm thickness  A) neck size 14"-19" (35cm-48cm) - Nose size 8"-11" (21cm,-28cm) B) Neck size 15.5"-21" (40Cm-54cm) - Nose size 9.5"-14" (24Cm-36cm) C) Neck size 18"-24.5" (46Cm-62cm) - Nose size 12"-15.5" (30Cm-40cm) D) Neck size 20"-29" (51cm-73cm) - Nose size 12.5"-17.5" (32Cm-44cm