This round double concave high optical purity glass lens measures 2 inches (50mm) in diameter and approximately 14mm thick, with a 50mm focal length. Designed for physics and educational use; thickness may vary slightly as consistency is not critical for educational applications. Minor cosmetic imperfections may be present but do not affect optical function. Suitable for physics classroom demonstrations of light divergence and concave lens behavior. Bulk lens and mirror sets available upon request.