The Polar Bear Urban Canteen is forged in steel! Our Urban Canteens are copper-plated, double-wall, 18/8 premium stainless-steel, vacuum insulated beverage containers. The unique copper-plated steel design prevents thermal radiation transfer, making the Polar Bear Urban Canteen the most well-insulated beverage container that you can own. If it’s not COPPER-PLATED, then it’s NOT a Polar Bear!