Feature: 1. High Light Transmittance and Refractive Index: The lens is coated, has high light transmittance and high refractive index, making the image brighter and clearer 2. Standard and Universal: The screw interface size is the international standard RMS size, which can be used by 95% of professional biological microscopes on the market 3. High Quality Brass Material: Made of brass material with exquisite workmanship, this objective is corrosion resistant, can no worry about falling down 4. Chrome Plated Shell: The shell of the objective is chrome plated, which is wear resistant, stable and durable, can use for long time 5. Application: This microscope objective as the important fitting of microscopes in laboratory, mainly used for microscope magnification to observe objects Specification: Item Type: Achromatic Microscope Objective Material: Brass Model: 4/0.10 Use: Microscope Accessories Interface Size: Approx. 20.2mm/0.8in (International standard RMS size) Magnification: 4X Numerical Aperture: Approx. 0.10mm Cover Glass Applicable Thickness: Approx.0.17mm Microscope Applicable Mechanical Tube Length: Approx. 160mm/6.3in Working Distance: Approx. 0.13mm Common Rail Distance: Approx. 195mm/7.7in Parfocal Distance: Approx. 45mm/1.8in . Package List: 1 x Achromatic Microscope Objective1 x Storage Bottle