Nike Men's Free Train Force Flyknit Running & Training Shoes - Lightweight Gym Workout Shoes for Men with Breathable Comfort - Perfect for Jogging, CrossFit & Athletic Training

I almost returned these for the reason that others have criticized: the tightness of the heel and rubbing it causes. However, it broke in a bit after wearing it a couple times and now is ok. Note, however, I use it just at the gym... I would not use this to run it because the rubbing would make it prohibitive.