Eschenbach High Power Stand Magnifiers are ideal for any visual task that requires high magnification. Special Features: The transparent, plastic base lets in maximum light for clear, bright viewing. All have an open base base for writing underneath. Magnification/dioptric value/ideal eye-lens distance printed on all lens heads. Magnification: 6x. Diopter: 23D. Lens Size: 50 mm. Lens Type: Aspheric. Mount: High Grade White Plastic. Lens Material: PXM Plastic with Cera-tec Coating. Miscellaneous: Open Base for Writing Instrument. Lens-to-Image Distance: 300 mm. Enlargement Ratio/Transverse Magnification: 7.8x. Maximum Allowable Add: 3.3D.