As described in numerous reviews online. Very light shoes. Holds the back of the foot. plush feel. 4 mm fall off. Softens the blow, but not too much. I use it for 10,000 runs twice a week. I used to have Freedom Iso 1. They lasted about 600,000. Not impressed. Compared to previous versions, the 3 Series has much better grip on wet surfaces. The first time I repeat the shoes, well, 2 versions up. Very happy with the purchase. I wish there was more choice of colors or styles. I don't particularly like this combination. But it looks better than in the photo.