When I first saw this on TV, I tried ordering the size 5-1/2 but it was sold out the first few minutes of airing! Because I liked it a lot, I ordered the size 6 instead. When I got it, it was just too big that it slips off my foot. I returned the 6 and decided to go online to check for my size and lo and behold, they had the 5-1/2! I ordered it immediately and it just arrived today. It fits perfectly! The test is when I actually wear it to work tomorrow. Just happy I got my size!