Paying $645 for a pair of pants that wasn’t created by a well-known fashion brand might seem ludicrous, but what if that said pair of pants would last you forever? That’s the promise of adventure clothing brand Vollebak, which claims that its new “100 Year Pants” will last at least a century.

Vollebak cofounder Steve Tidball claims that the company stands behind the 100-year guarantee because the new pants are made of materials so tough you can walk through fire in them.

Technically, the 100 Year Pants are made of an innovative three-layer material designed to withstand various threats.

The outer layer repels water and is designed to resist abrasions, the middle layer is fireproof and also expands as an airbag at high temperatures, acting as a barrier between your legs and the flames, while the third layer is an aramid fibre, a nylon-related synthetic doesn’t burn or melt, offering extra protection.

“Most fire-resistant clothing is made from heavy, uncomfortable, chemical-laden materials, but this is the world’s first intelligent material that can be comfortably worn every day, then alter its behaviour in the face of fire,” Vollebak cofounder Nick Tidball said about the material. “It was originally designed to help soldiers handle the most extreme situations, but without having to dress like firefighters.”

Still, 100 years sounds like a long time for a pair of pants, especially if you wear them frequently? So how do you know they’ll last that long?

Well, Volleback put them through the Martindale abrasion resistance test, where a mechanical thumb is rubbed against the fabric until the fibres start to break.

A regular polyester fabric can survive around 25,000 revolutions, but the innovative material these pants are made of passed 100,000 cycles of wear and even then, it needed to be checked with a magnifying glass to see if any of the fibres had broken. Volleback claims they hadn’t.

The 100 Year pants are allegedly not only incredibly tough but also surprisingly comfortable. They are designed to stretch with your body, making them suitable for all kinds of activities, from mountain climbing to yoga, and are stylish enough to be worn on casual outings.

So if you’re looking to buy the last pair of pants you’ll ever need, these seem like a pretty good choice. $645 is a lot, but if you think about it, it’s just $6.45 per year. Now if you could manage to live for another hundred years to get full value that would be great.

Interestingly, this isn’t Volleback’s first 100-year clothing item. Last year, the company launched the 100 Year Hoodie, which was made of a softer version of Kevlar, and more recently, a jacket made of graphene jacket designed to absorb heat and repel bacteria, among other things.