Halti Size 1 Head Collar. Dual Action Training Aid That Turns The Head Discouraging Pulling And Allows The Dog To Train Itself To The Futility Of Forging. Also Great As An Instant Bite Restraint For Aggressive Dogs. For Jack Russell, Standard Dachshund, Medium Poodles, Sheltie, Welsh Corgi, Westie, Whippet, And Other Medium Small Breeds.