My 1894 CSBL came with those XS sights and rail.
If you can see a handgun front sight in focus, the XS front sight should be in focus for you and the ghost ring sight should work well enough.
If a handgun front sight is a bit blurry, the XS front sight will be a bit blurry as the rear ghost ring is large enough not to enhance the focus of that front sight like smaller aperture sights can do.
I'm about to order
this so I can install smaller apertures which will give me the choice of more accuracy, or remove the aperture for more speed/low light usage.
However, it looks to be the aperture post only. From some internet research, my spare Williams apertures for my other guns will fit.
My CSBL came with the
long stem 0.191" ID aperture. It looks like the
CST comes with
short stem apertures and has one more size to choose from at XS.
https://www.xssights.com/products.aspx?CAT=9184