I tried 10.5W and they were too small and narrow which is my normal shoe size. I returned it and increased it to 11 watts but they were still too tight. The left side of this second pair turned out to be "wide", but the right side was not, despite being marked as such. Unfortunately, I don't think this brand is what it used to be. I had a very comfortable pair a few years ago. They were very durable and felt great, but they feel like a completely different product.