Acknowledging my limited experience with slides in general, these seem to be pretty decent quality. I wear them mainly without socks, and primarily as house shoes or for quick trips to the mailbox or take out my dog. I typically wear a size 11.5 and opted for the XL (L says 10/11, and XL says 12/13) and they fit me about how I would expect a 12 to fit. I have to adjust the straps a bit further than I would prefer, but that only impacts their looks and my wife didn't even notice they were any different. I can't speak to how the large would fit, but the XL is fine for an 11.5 foot. The soles were a bit hard/stiff at first wear, but the material has somewhat broken in over the first month or so and are much more cushiony now.