These are very popular in Asia as a feature ingredient in soups and stews. They are recovered from the lower shank leading into the foot. They can also be used as a more convenient substitute for Calf Foot. The larger of the two photo specimens was 13-1/8 ounces and 12 inches long, the smaller 7-3/4 ounces and 10 inches.
More on Beef Shanks
Buying: Here in Southern California these can be found in the meat section of larger markets serving an Asian community, particularly Chinese and Philippine. They are packed on foam trays weighing about 1 pounds. Freezing them for longer storage will not harm them.
Prep: Rinse and cut is about all that's needed. For most recipes you will cut them crosswise about 1 to 1-1/2 inches long, then split the two tendons apart and then split the individual tendons in half lengthwise. Other recipes cook them whole and slice them crosswise.
Cooking: For use as a feature item, you need a total cooking time of 2-3/4 to 3 hours. For use to enrich soup stock (in place of Calf Foot, for instance) a much longer cooking time is needed. They should nearly dissolve.
Yield: Just about 100%.