Grisport’s Grizzly leather Winter Boot is built on the Vibram Megagrip Pro outsole, which provides a high level of performance in both grip and durability in a wide range of temperatures (from -40°C/-40°F to +250°C/480°F). The Megagrip Pro outsole satisfies the ISO standards for protective outsoles which includes metrics for tear strength resistance, oil resistance, hot contact resistance, and flexing resistance.