A state-of-the-art, outer casing material that's a high impact resistant, cross laminated plastic film. Strong enough to even protect explosives during transport. PLUS, it's tamperproof, proven to secure even critical legal and automotive labels. In other words, it's really tough material. We've combined it with a resilient, repositionable layer for the insole, to help stabilize the wrapped hoof inside the boot, with or without caulks or shoes.