These are a pair of brand new focusable extreme widefield high-eyepoint 30mm WF15X microscope eyepieces with 16 mm 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. Features & Specifications: Focus Adjustable 15X Magnification Power 16 mm Super Wide Field of View 30 mm Mounting Size (in diameter) High Eye-point Design