Got my set up from Hical. It's two separate items,a side rail to mount your optics mount/rail to plus the mount itself. I have a VZ58 in 556 though which is already drilled and tapped for the side rail. For a CZ858 you'd have to drill and tap yourself or have a gunsmith do the work. Check out the VZ58 optics sticky it'll give you some ideas as well. Nothing wrong with the rear sight mount and scout scope combo either.