The beef knuckle is spherically-shaped and consists primarily of lean meat. It consist of four parts: the inside knuckle muscle, slightly deep in color and tender, the knuckle main muscle that has muscle running into the center, is fine textured and tasty; the outside knuckle that is deep color and slightly tough; and the tri-tip that has some marbling but is not as tender as would be expected from the appearance. 
 
Cut into small bits, it's great for training use into enticing them to learn with success! It's a great treat indeed!