I received a pair of Crocs as gifts a few years ago. I love them but they are falling apart so it's time to order new ones. Their sizes are strange. I had no idea what to buy so I made an educated guess and believed. Luckily I got lucky and got the right size. I usually wear a size 7 1/2 women's shoes and these 5M(D) Mens / 7M(B) Womens (whatever that means) fit perfectly. They also fit European sizes 37-38 if that helps anyone.