Unlike real tissue, human tissue simulant doesn't snap back: The cavity remains, allowing ballistics types to judge, and preserve a record of, a bullet's performance. Plus, you don't need to autopsy a block of human tissue simulant; because it's clear, you just walk up to it after you've shot it and take a look at the damage. Following which, you can take it home, eat it, and enjoy stronger, healthier nails in thirty days.