39.5 which is supposedly US 9.5 but European, so I’d say runs slightly smaller. I’m a US 8.5W or 9 typically & would have preferred these in a size 40 for comfort. Does have slingback style with elastic though. They do have some wear-especially on the back heel, but not super noticeable when wearing. Think I only wore 2-3x. There’s also an odd thread holes on back-no idea why.