These Thorogood Rubber Structural Bunker Boots have a flame and heat resistant rubber upper, and a 3.5mm polyester felt liner with heel reinforcement. The insole is a removable Superknit covered polyurethane footbed, the midsole has a stainless steel puncture resisting bottom plate, and a steel triple ladder shank, with a flame and heat resistant white Traction Lug outsole.