If you are looking for professional optical lens, then your research is over here. That’s because our product can meet your need. Adopted of , it is practical and durable for long time use. It is not easy to get deformed. Features -Color:Transparent -Material:PMMA -Size:4.20X4.20X0.75cm/1.65X1.65X0.29in -Diameter: 42mm -Center thickness: 7.5mm -With edge/edge thickness: 2.0mm -Focal length: 68mm -Object distance: 53mm -Magnification: 4.7 times -Light transmittance: above 93% -Temperature: -30 degree centigrade+85 degree centigrade -Excellent for physics classroom demonstrations in optics and light refraction. -Also suitable for reading newspapers, books, magazines, maps, science, jewelry, inspection, rocks, handicrafts and so on. -Highly polished with ground edges, will not hurt your hands when use it. -There are sufficient quantities to meet your replacement and usage needs. -Made of premium and , which is durable and wear resistant. Package list: 20 x convex lens