I think I had size 10 or maybe 11 Rock boots on my DUI. They were too big for XL jets, and too small for turtles. I have since put turbo soles on the suit, and got bigger spring straps and they seem to work with XL jets. For size 10 Rock boot, it seems to be hit or miss with XL jets. You really have to try them on. I have heard some people can get them on, others think they are too snug.... YMMV...