Do you want your students or children to measure the refractive index of glass? Then, you miss our optical triple-prism. Made of glass material, it is safe and durable. Suitable for home, school, and other places in need. Features -Color: Black -Material: Glass -Size: About 16.00X12.50X10.00cm/6.29X4.91X3.93in - Smooth surface, no burr, stable longevity. They are not easy to damage. - Also, it can be a nice birthday gift for your friends who do experiments. They will like it. - Lightweight and compact, it is very convenient for you to carry. Also, it will be a great addition to your laboratory supplies. - Fine workmanship and creative appearance ensure its popularity and practicality. - Perfect and suitable for school classes teaching tool or as intellectual development toy for children. Package list: 1 x Triple Prisma 1 x Bracket