Once the holosight is zeroed, flip the mag in place and center the reticle in the field of view with the adjustment screws on the mag base. Then flip it out of the way and flip it back. You will have to repeat this a couple of times before you get it where you want it and it stays there. After that, no problems. It stays there. You don't have to re-zero it to use the mag. It retains the zero from the non-magnified aspect as is consistant with a holosight. The magnifier does enlarge the reticle, but it is appropriate with the sight picture. It also clarifies the reticle making it much sharper. It really does improve your potential accuracy. There is no adjustment for the shooter when changing from magnified to non-magnified. It's really nice that way. It still has a good field of view under magnification as it is just like looking through a 3x scope ('cause it is). And that is exactly what it is like, looking through a 3x power scope with an electronic reticle. The picture is very clear and sharp on the magnifiers (for those concerned about the quality of the glass). The unit itself is beefier and much more sturdy than I imagined. And a little bigger than I had expected, which was good for me as some of the pictures make it look small.