Whether you're training for a marathon or just enjoying a casual run, the Nike Air Zoom Pegasus 41 is the ideal all-round running shoe. Take on your running challenge with the Air Zoom Pegasus 41. Midsole The midsole is made of ReactX foam. Compared to Nike React foam, ReactX is designed to reduce the carbon footprint of a pair of midsoles by at least 43% due to the reduced energy used in the manufacturing process, and to increase energy return by 13%. Zoom Air units are built into the midsole. These absorb shock and bounce back quickly, reducing the stress on your muscles, joints and tendons. You can run faster and jump higher with the Zoom Air Unit because it transfers energy more efficiently. Upper The mesh upper makes the Air Zoom Pegasus 41 very breathable. Outsole The shoe has a rubber outsole and offers good grip and traction while running. The outsole also has flex grooves to create more flexibility in the forefoot. This shoe has Nike's characteristic waffle pattern as an outsole, with short rubber studs in the shape of honeycombs, for grip on wet and dry surfaces.