These are the 100 Year Pants. The manufacturer, the adventure clothing brand Vollebak, claims that the pants will last a century because the materials are so tough, you can walk through fire in them. “The only pants more advanced than these are on spacesuits,” the company says.

An overstatement? Probably. But according to Vollebak’s cofounder Steve Tidball, the company did in fact look to astronaut clothing, in addition to military gear, to design the pants.

The pants are made from an innovative, three-layer material. The outer layer is designed to resist abrasions and can repel water. The middle layer is fireproof and automatically expands, like an airbag, if it touches any flame, putting a barrier between you and the fire. The inner layer is made of aramid fiber–a nylon-related synthetic that can’t burn or melt.

The material was developed by the Swiss brand Schoeller, a 150-year-old company that develops protective textiles for the military and police, in addition to other high-performance fabrics. “It was originally designed to help soldiers handle the most extreme situations, but without having to dress like firefighters,” says Vollebak cofounder Nick Tidball. “Most fire resistant clothing is made from heavy, uncomfortable, chemical laden materials, but this is the world’s first intelligent material than can be comfortably worn every day, then alter its behavior in the face of fire.”

This isn’t the first time Vollebak has made big promises about its gear. The company previously released a hoodie that it claimed was indestructible, and more recently, it unveiled the world’s first graphene jacket, which is designed to do everything from absorb heat to repel bacteria. Are the garments as tough as Vollebak claims? You’ll just have to live another 100 years to find out.

The 100 Year Pants are available now for $645, although they have already run out of stock for extra-small and small sizes. It seems expensive until you realize you that it’s only $6.45 per year. Just make sure to leave them to someone your size in your will.