The Adidas Ultra the exact same design features as the Ultra SL, except the nylon mesh used on this shoe is more breathable. The Prolite Full Carbon sole is profiled in it's thickness to put the muscle under the cleat, and thinner on the edges to make for a very comfortable and stiff shoe. At 7.5mm, the stack height is about as low as you'll find on any cycling shoe. The Fast Strap SL and micro-adjustable buckle system ensures an even fit with no hot spots.