Comfort. Safety. Flexibility. Everything you need in a work boot for those 10 to 15 hour shifts. The Carbo-Tec outsole is made of durable, long-lasting rubber and is chemical-and oil-resistant. All day comfort is provided by theComfort Core insole.This technology includes a polyurethane energy return heel plug that stores energy as it's compressed by your foot, then releases energy as you lift your foot. It also has an Air Flow System that forces air through the footbed as you walk to keep your feet cool and dry.