First of all, the Gentle Leader"_ Headcollar is NOT a muzzle. When fitted properly, your dog is free to open his mouth to eat, drink, pant, fetch, bark and even bite - except when you close his mouth by pulling on the leash. The Gentle Leader"_ Headcollar features two soft nylon straps - the collar portion fits high at the top of the neck, and the nose loop fits loosely and comfortably across the base of the muzzle. Each strap has a distinct and important effect The Noseloop: The Gentle Leader's patented 'Nose Strap' applies gentle pressure in the same way a dog's pack leader would grasp a sub-ordinates muzzle. Your dog learns in his own language that you are the leader. The Neckstrap: Puppies will melt in relaxation when their mother picks them up at the back of the neck. Gentle Leader uses this pressure point to work with your dog's natural relaxation instinct. With this gentle pressure at the back of the neck the dog pulls backward not forward which corrects leash-pulling forever. Prevents Jumping Teaches Sit Controls Barking Not a Muzzle Stops pulling and lunging Ideal for growing puppies FEATURES Reduces pulling on the leash Perfect for training dogs to heel Easy to fit and get dog used to wearing it Collar sits high on dog"_s neck without putting pressure on the throat Nose loop redirects dog without the need for a muzzle Comes with detailed instructions and a training DVD SIZE CHART Small 5 - 10 kgs - Beagles, Jack Russells, Shelties, etc Medium 10 -30 kgs - Dalmatians, Pointers, Spaniels, Sight Hounds, etc. Large 30 - 55 Kgs - Danes, Goldens, Labs, Rotties, Shepherds, etc.