The Crab knife is very useful in opening up the shell of a king crab leg. The point of the tool can be penetrated into the soft spot on the king crab leg right at the knuckle. Once inserted the tool can be wiggled down the center of the leg like a manual style can opener. It's not necessary but can make getting into the king crab leg a lot easier. This product is 1/2 inch in length, reusable and hand washing is recommended.