Quality Optics - Optical Glass Multi Lens Head Visor Magnifier Jewelers Loupe Binocular (3.5x)

Lens exchange/installation directions: Tab mount: using the flat side or butt of a screwdriver, gently push out tabs from the inside of the magnifier, align new lens and reinsert tabs. Screw mount: first verify screw holes are spaced 3 ¾" on center. Remove screws and lens. Insert new lens and fasten screws, do not over tighten. Posted working distance of lenses are approximate and can vary slightly with the user's vision, head size/shape.