A boning knife's primary purpose is to remove meat and trim meat and fish from the bone. Boning knife blades vary in length from 4" to 7". Many cooks simplify carving and get extra servings by boning out a roast when it is partially cooked. For boning roasts, whole hams, lamb legs, veal legs, and filleting fish, a narrow flexible boning knife blade is best. The wider stiff blade on a boning knife is used for cutting raw meat and many other trimming operations on less thick cuts of meat.