Feature: 1. BRIGHTER AND CLEARER IMAGE: Lens after coating bring high transmittance, high refractive index, possess brighter and clearer image 2. WITH PROTECTIVE DEVICE: Spring protection device can automatically rebound when the cover glass is encountered during observation, to protect the lens from crushing the specimen 3. CORROSION RESISTANT BRASS: Brass material with fine workmanship, corrosion resistant and not easy to fall, exquisite and durable, the shell is chrome plated with accurate materials 4. UNIVERSAL SCREW INTERFACE: The screw interface size is the international standard RMS size, which can be used by 95% of professional biological microscopes on the market 5. 40X MAGNIFICATION: This is a 40X high magnification objective, helps a lot in study, work or research, useful, helpful and practical 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 Lens1 x Storage Box