This is a brand new super widefield high-eyepoint WH10X/20 microscope eyepiece with reticle. It is graduated in 1mm. It is Achromatic (International DIN/JIS) standard size with outside diameter of approx. 30 mm. It fits most common size stereo microscopes. Give your microscope a boost with greater power & clarity at a fraction of cost. Features & Specifications : 10X Magnification Power 20 mm Super Wide Field of View Graduated in 1mm Overall Reticle 100mm 30 mm Mounting Size (in diameter) High Eye-point Design.