Under Armour Men's UA Spine Hybrid Training Shoes Synthetic Upper uses light, supportive foam sandwiched between durable ripstop on top &#38; breathable mesh below Synthetic overlays for stability &#38; to lock in your midfoot Die-cut, full-length 4D Foam&#174; sock liner for added comfort &#38; a custom fit UA Spine&#8482; technology in the heel creates an incredibly light, flexible feel without sacrificing support Full-length Micro G&#174; foam turns cushioned landings into explosive takeoffs