This one-of-a-kind boot is the first in the industry to provide a flexible metatarsal guard. It's a tough Cat boot featuring d3o materially to provide ''intelligent shock absorption.'' d3o is flexible until impact, at which point the molecules lock together to absorb shock and resist the force of impact, giving your foot the ultimate protection. ASTM F2413-11 I/75 C/75 EH. Cat Steel Toe boots and shoes are rated ASTM F2413-05 I/75 C/75 - the highest available strength for impact and compression. Proprietary iTechnology construction for superior durability and comfort. Full grain leather upper. Nylon mesh lining. Ortholite sock liner. EVA heel cushioning midsole.