Super security heel and toe double locking system. Heavy laminated steel body plates are chrome plated for maximum rust protection. 8 hardened steel chrome plated assembly pins. Rockwell case hardened chrome plated steel shackle. New long lasting protective vinyl bumper. Stainless steel "Inox" springs. 5 pin brass cylinders. Anti-pick top quality brass mushroom pins. New grey headed keys for easy grip. Paracentric designed keyways to restrict tampering and picking.