Material: K9 crystal, Which offers a high refractive index and high clarity. Specification: Diameter: 80mm(3.15"), height: 38mm(1.5"), net weight: 307g(10.8 oz). Easy to use: This dome magnifier has smooth surface,make it glides effortlessly across any surface. Various useage: Perfect for reading newspapers, maps, contracts, architecture plans, negatives, documents, and other reading material! Dome magnifier: also known as a hemispherical magnifier or bright field magnifier, is a light gathering magnifier that is uniquely shaped in a half circle.