This is a brand new black 100X Achromatic microscope oil immersion objective lens with protective container. It is a standard (International DIN/JIS) lens. It fits common size (DIN/JIS standard) compound / biological microscopes. Give your microscope a boost with greater power & clarity at a fraction of cost.
When light passes from a material of one refractive index to material of another, as from glass to air or from air to glass, it bends. Light of different wavelengths bends at different angles so that as objects are magnified the images become less and less distinct. With "dry" objective lenses this loss of resolution prevents using magnifications of above 400x or so