I purchased the Extra Large for my size 13 running shoe, and they barely fit. I had to give them a good yank/pull to get them around my running shoes. So I suggest buying at least one size higher than the chart suggests as I did. My review today is based on a ten mile run I performed yesterday after a snowfall a few days earlier. My run took place, mostly on asphalt and concrete. I started the run not knowing what I would get, so I wore the YakTrax just to make sure if/when I hit icy patches I wouldn't slip. At my age, I just can't take a fall, and I don't want to injure myself. More to the point, I want to run happy and confident, even on ice. So they worked very well. My running gate with them on was normal and easy. I even forgot I was wearing them after the first few minutes. I would say that 90% of my run was on bare concrete and asphalt, because it turned out the sun had cleaned up most of the snow before folks had packed it down. So I really gave the little spikes a hard workout. First, the YakTrax overlays did not fall off. Hooking up the toe strap and securing the velcro strap did the trick. Second, the carbide steel spikes show relatively little wear after ten miles of brutal running on the hard stuff. I imagine that if the conditions had been the other way around and I ran on 90% ice and 10% hard surface, there would be no visible wear on the spikes whatsoever. The wire coils on the rear look great too, although I am not a heel striker. I look forward to wearing the YakTrax again the next time I want to go out for a run and I'm looking at icy conditions. They have earned my confidence on ice. There were only two drawbacks. First, about nine miles into my run, I began to notice my left little toe rubbing on the inside of my Hoka AT Challenger 5s. I was initially concerned that my shoes were too small, but that didn't make sense since I've worn these for more than a year! Then I remembered I was wearing the YakTrax. Recall that even the extra large are tight on my size 13 foot. So I stopped and took off the YakTrax and the pain went away. So the next time I wear them, and I'm looking at a run of more than 8 miles, I will see if I can adjust the fit so that there is less impact to the soft sidewalls on the outside of my Hokas. Recommendation to the manufacturer: Please offer an XX Large. I'd probably buy that for my size 13, which would be sizing up TWO LEVELS vs. the size chart. Second, as I said, the carbon steel spikes were stellar, and very little wear after my run. But one tiny spike, on the left Yaktrak was smashed over on its side within it's plastic support base. The metal didn't give way, but the plastic disc supporting the spike gave way, and the metal did a "leaning tower of Pisa" slanting over to one side. I weigh 195 lbs, so I probably gave that spike a massive lateral force while running on raw concrete/asphalt. Even in its bent over position, the spike is still giving me anti-slip capability, so at the moment I'm not worried. So, overall, I had a good experience.