Description Adopting great quality material, which lets you use it for a very long time. Though it is simple in design, it's so practical when you use it. The excellent workmanship of our product will bring you a good experience. Easy and convenient to install and use, it is a very useful achromatic objective lens. Features - Color: Silver. - Size: 6.00X4.00X4.00cm/2.36X1.57X1.57 inch. - Material: Steel. - Magnification: 4X. - Cover glass Thickness: 0.17mm. - Working distance: 18mm. - Mounting size: 20.2mm（standard RMS thread). - Numerical aperture: 0.1mm. - Made of material for a long time and durable use. - Smooth surface and nice polished, neat and generous, so don't need to worry about harming your hand. - Steel shell is precision machined, stable and durable for long time use. - This is a achromatic objective lens for biological microscope. - Increase contrast: It can unwanted reflections and increase contrast. Made of material for a long time and durable use. Smooth surface and nice polished, neat and generous, so don't need to worry about harming your hand. Steel shell is precision machined, stable and durable for long time use. This is a achromatic objective lens for biological microscope. Increase contrast: It can unwanted reflections and increase contrast.