Features With Protective Device: The 40X high power microscope lens is equipped with a spring protective device, which can automatically rebound when encountering the cover glass during observation, preventing the lens from crushing the specimen. Fine Workmanship: The microscope lens has the characteristics of fine workmanship. It is made of brass material, which is durable and not easy to drop. The shell is chrome-plated. Brighter and Clearer Images: The objective coated lenses have high light transmittance, high refractive index, and brighter and clearer images. 40X Magnification: This is a 40X high magnification objective lens, which is of great help for study, work or research, and is a useful and practical tool accessory. Universal Threaded Interface: The size of the threaded interface is the international standard RMS size, which can be used by 95% of professional biological microscopes on the market. Specification: Item Type: Achromatic Microscope Objective Model: 40/0.65 Material: Brass Use: Microscope accessories Interface Size: Approx. 20.2mm / 0.8in (international standard RMS size) Numerical Hole Diameter: 0.65mm Cover Glass Applicable Thickness: 0.17mm Microscope Applicable Mechanical Tube Length: Approx. 160mm / 6.3in Working Distance: Approx. 18mm / 0.71in Common Rail Distance: Approx. 195mm / 7.68in Parfocal Distance: Approx. 45mm / 1.77in Spring: Yes(automatic rebound) Package List: 1 x Lens 1 x Storage Box Package List 1 x Lens 1 x Storage Box