This round concave glass mirror is designed for physics and educational uses. It is approximately 3" (75mm) diameter and 3mm 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

This round concave glass mirror is designed for physics and educational uses. It is approximately 3" (75mm) diameter and 3mm 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 Round concave glass mirror designed for physics and educational uses.