The Structure 25 offers stability and cushioning in strategic areas to accompany you on every run, mile after mile. The support offered by the shoe is a guarantee of stability for your natural stride. Adjusted support and carefully targeted cushioning let you feel secure with every step. Structure 25 is Nike Running's most stable shoe. With its new foam midsole, wider midfoot support and more pronounced rocker shape, it offers a more stable platform and smoother transitions from heel to toe. The thicker the underfoot cushioning, the smoother and more comfortable your stride. Cushioning absorbs shock when your feet hit the ground. The new midsole incorporates improved foam for an incomparably supple, comfortable feel. Thick foam ensures total comfort. The pendulum-shaped foam provides support for all three phases of the stride. It offers optimum flexibility during impulse, a fluid stride as your foot moves forward and perfect cushioning during contact with the ground. The more responsive the shoe, the greater the energy return with each step. If you want to run a little faster or with a little less effort, reactive shoes are ideal. They give a little more rebond and let you get the most out of your run. A Zoom Air unit in the forefoot provides responsive cushioning. Each stride creates energy feedback that propels you forward with a dynamic, responsive feel. The generous forefoot offers ample space for your toes. It also offers a wider base and a fluid stride. The reinforced structure and heel wrap guarantee a more secure fit. The new, improved foam underfoot further enhances support. Softer materials have been used inside the heel, collar and tongue, so that all parts of the shoe in contact with the ankle feel soft and comfortable. A single layer of mesh provides breathability and durability. The durable rubber outsole features grooves in the forefoot for flexibility and vertical grooves on the sides for stability.