In 1897 Catholic priest Casimir Zeglen developed a bulletproof vest made from tightly sewn silk, linen, and wool. He tested it publicly on himself, and it worked. The product cost about $6,000 (adjusted for inflation), making it impractical for most people, but bulletproof silk did save the life of King Alfonso XIII of Spain during an assassination attempt. Within a few decades, advancements in weapon technology rendered the silk bulletproof vest useless.