I've accumulated a lot of Keen shoes & walking boots since the company first started - they don't wear out! These are narrower than all the other Keen styles I have, and I have quite wide, rather problematic feet and usually appreciate Keen's roomy toe box. I didn't have very high hopes for these fitting well and I tried them in a UK 4.5. 5 and 5.5 - I have Keen shoes in all these sizes. I chose the 5.5, which are very slightly long, but am surprised at how well they've moulded to my feet, though I'm not accustomed to needing to break in Keen shoes, which I've needed to with these. Adjustment via the lacing is useful. Am enjoying wearing them, they're very comfortable & springy. I love the style & colour (the denim blue shade), and am also finding the shoes are extremely well made and very versatile. Also superb for walking where full-on walking boots aren't necessary. Highly recommended!