3x+6x=9x Aplanatic Achromatic Zeiss Optics D36 (3x+6x=9x) Aplanatic Achromatic Pocket Magnifier Z00004, this large diameter (22mm, approx 7/8") double folding loupeimage from Zeiss Optics is the most versatile portable Magnifier used by hobby people and for jewelry repair. Use the individual 3X or 6X lenses for larger subjects, or combine the lenses for 9X magnification. It's an ideal choice for stamp and coin collectors, archivists, antique dealers, and medical research.