This is Twisted X's first FIRE RESISTANT (FR) rated boot. Due to a lack of US FR boots standards, we have adopted the approved European standards. European safety standards (ANSI). The rubber outsole, puncture resistant midsole, welt, kevlar welt stitch, vamp, and shaft leathers stitched with Kevlar thread, and laces all meet European FR safety standards. We've also added a reflective strip on the back counter and shaft. We developed "TX's Quick Zip" for easy and quick entry and exit. Our FRX boot is EH rated and WATERPROOF. This is the "mac daddy" of FR footwear.