This optical lens for magnifier adopt detailed workmanship, withstand long time using. Compact size, easy to take, use and clean, you will feel the convenience of them. The lens is of suitable size, makes it good for many using scenes, owning good magnifying effect. Features - Color: Transparent - Material: glass - Size: 4.20X4.20X0.75cm/1.65X1.65X0.29in -Focal length: 68mm -Object distance: 53mm -Magnification: 4.7 times -Transmittance: more than 93% -Temperature: -30 degree centigrade+85 degree centigrade - Made of detailed workmanship, these optical lens are with high durability to be used for long time. - Well polished, smooth surface, will not hurt hands when used, you can use the convex lens with more confidence. - Light weight and compact size, the optical lens is easy to carry and store, you will feel the great convenience. - These optical lens owns good magnifying effect, with clear observation, a must-have replacement for the broken magnifier lens. - Clear design, the convex lens is highly practical, good for both teaching and studying. Package list: 30 x magnifying glass