From the perspective of the normal orientation of the pistol, with the slide stop lever being on the left side of the frame, for example ...
Removed left-to-right.
Installed right-to-left.
Care must be taken not to damage the tritium capsules during installation, of course. (Or damage the ejector depressor plunger spring or firing pin safety plunger spring, of course.)
An earlier set of Ashley Big Dot sights on my CS45 (before the rear tritium capsule was offered).