Concave Mirror - Glass, dia 50mm, Focal length 300mm-EIS-PH0520F offers a thoughtfully designed, durable resource for hands-on learning. This round concave glass mirror is designed for physics and educational uses. It is approximately 2" (50mm) diameter and 1.8mm 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. 300mm Focal Length Bulk lens and mirror sets available upon request. Round concave glass mirror designed for physics and educational uses.