These are a pair of brand new focusable extreme widefield high-eyepoint 30mm 20X microscope eyepieces with 12mm field of view. They are Achromatic (International DIN/JIS) standard size with outside diameter of 30 mm. They fit most common size microscopes including Nikon, Olympus, Zeiss and Leica. Give your microscope a boost with greater power & clarity at a fraction of cost. Features & Specifications: Focus Adjustable 20X Magnification Power 12 mm Super Wide Field of View 30 mm Mounting Size (in diameter) High Eye-point Design