Welcome to our store! 1. CLEARER AND SHARPER IMAGE: Lens after coating provides high transmittance, high refractive index, resulting in a brighter and clearer image 2. PROTECTION MECHANISM: The feather protection mechanism automatically cushions when the cover glass is encountered during observation, protecting the lens from cracking the specimen 3. CORROSION-RESISTANT BRASS: Brass material with fine craftsmanship, corrosion-resistant and not easily broken, exquisite and durable, the casing is chrome-plated with exact materials 4. UNIVERSAL SCREW THREAD SIZE: The screw's thread size is the international standard RMS size, compatible with 95% of professional biological microscopes on the market 5. 40X MAGNIFICATION: This is an objective lens with 40X high magnification, helpful for studies, work or research, practical and useful Product type: Achromatic microscope objective Model: 40/0.65 Material: Brass Usage: Microscope accessories Thread size: Approximately 20.2 mm / 0.8 in (international standard RMS size) Numerical aperture: 0.65 mm Cover glass applicable thickness: 0.17 mm Microscope applicable mechanical working length: Approximately 160 mm / 6.3 in Working distance: Approximately 18 mm / 0.71 in Common rail distance: Approximately 195 mm / 7.68 in Parfocal distance: Approximately 45 mm / 1.77 in Warranty: Yes (automatic rebound) 1 x lens 1 x storage box Customers are our highest priority. If you find any issues with your product after receiving it, such as damage or incorrect quantity, please contact us immediately. We strive to provide you with the best post-purchase service.