Convex Mirror - Glass, dia 50mm, Focal length 75mm-EIS-PH0526B offers a thoughtfully designed, durable resource for hands-on learning. This round convex glass mirror is designed for physics and educational uses. It is approximately 2" (50mm) diameter and 2mm thick. Note, thickness varies as they are not designed to be consistent in that respect. Because of their educational use design, there may be minor imperfections that do not affect physical function. 75mm Focal Length Round convex glass mirror designed for physics and educational uses.