The Primary Arms 3X Red Dot Magnifier (GEN III) is waterproof and fog resistant. Place the magnifier behind your red dot or holographic reflex sight to instantly magnify the sight picture at 3x power. The integrated diopter provides a fast focus ability to keep the image clear. Azimuth and elevation adjustments keep the dot centered in your field of view. This tough magnifier features a 1-year warranty. NOTE: Make sure that the mount you choose is capable of interfacing with the 30mm ring on this magnifier, because the objective is larger than the 30mm mounting area. Mounts intended to just slip over a 30mm mounting area and tighten down will not work.