I bought these in 4 colours; blue black, green, and pink. They looked like the style of socks I normally go for and I liked the selection of colours. I checked the size guide which told me a S/M was equivalent to a UK 9-11. I'm a 9.5 so duly ordered them in an S/M. If you're an 11, or even a 10, th...ere's zero chance these will fit you; they only just fit me. The shafted of the sock is about an inch or so shorter than I would like it to be. It's a shame as they're nice quality socks and they look great, but I'm now stuck with 4 pairs of socks that don't really fit. Fortunately I got them half price but some of the options I bought are now sold out, or I'd have probably bought them again in the larger size