The Gentle Leader Calming Cap is a new behavior management aid that is designed to lessen a dog's anxiety or aggression in high-stress situations. The Calming Cap was designed by Trish King, CPDT CDBC and director of Behavior & Training at the Marin Humane Society, in collaboration with Lisa Moore, CPDT. The Cap was developed originally to ease hyperactivity in a dog that became agitated while traveling in a car. Since then, pet owners and professionals across the pet industry have used the Cap to quiet and calm anxious or excitable dogs. How It Works: The Calming Cap reduces the visual stimulus that makes a dog agitated by filtering his vision. The single-panel sheer fabric window makes the dog's vision indistinct, while allowing the dog to easily navigate his surroundings. Quality Features: Single-panel sheer fabric window offers enough vision to confidently navigate surroundings while reducing the provoking stimulus. Soft fabric and elastic fit provides maximum comfort. Two Velcro strips wrap around the collar allowing for easy on/off use. Available in four sizes! Petite - Most Toy Breeds, Puppies; Small - Shelties, Most Small Terriers, etc.; Medium - Cattle Dogs, Female German Shepherds & Rotties, etc.;Large - Mountain Dogs, Male German Shepherds & Rotties, etc.