This is a 10X achromatic objective lens with black finish for certain infinity-corrected microscopes. Intended primarily for biological applications, it is designed to work with infinity-corrected microscopes using RMS mounting thread 45mm parfocal distance. Achromatic correction provides improved color accuracy and resolution. Compatibility Optical System Infinite Reference Focal Length 180mm Mounting Thread RMS 20.32mm Parfocal Distance 45mm Lens Specifications Magnification 10X Numerical Aperture 0.25 Corrections Achromatic Cover-glass Thickness — Nosecone Fixed Immersion Medium —