Under Armour Micro G Defy Running Shoes UA HeatGear Fabric - Wicks away sweat to keep feet cool and dry. Lightweight Synthetic Support - Lightweight support structure allows for high reflexivity and great mobility without adding weight. Micro G Foam - Thin and Light, it helps rebounds your heel-strike energy, creating forward momentum. 4D Foam - Moulds to foot for a locked in, comfortable, customized fit. Non Marking Outsole - Ensures you don't leave any traces behind.