I did not fit it to a SC, but I did fit one on a Para. I went to the website and got the telephone number and called. the tech person was very nice and told me exactly what to order. If your eyes are bad the big dot helps, but it does cover a lot of area.
I have XS24/7 tritium night on two pistols and will probably fit them to more. I have Big Dots on one and standard dot on the other. First set was ordered as Bid Dots and I didn't realize for several months I had the smaller. Really doesn't matter!
No S&W pistols with them, but the note above about telephoning for the right model is good advice.
If you can't fit the XS sights the Novak Dot over Bar is my other choice.
No confusion with either system as to "which is the front sight?"