LIAF,
Is the Z a red dot or is it a holographic type sight? With the red dot the dot appears to be on the lens of the sight when you look through it but with the holographic sight the dot appears to actually be on the target. Not sure how they accomplish the illusion of projecting the dot, but it gives a much better image.
A lot of the cheaper sights you see advertised as holographic are really just plain old red dots. The good holographic sights tend to be expensive.
If you look through a cheaper red dot and a good holographic sight side by side the difference becomes apparent. The higher price suddenly seem worth it.