Abstract: A shank assembly adapted for use with an interchangeable mouthpiece is provided wherein the shank assembly comprises upper and lower shank portions that may disconnect to permit removal or replacement of the interchangeable mouthpiece, and re-connect and lock to secure placement of the mouthpiece. An adjustable bit kit is also provided comprising sets of upper and lower shank portions of different lengths which may be combined to form various shank assembly portion ratios in accordance with the training, comfort and response needs of the bridled animal.