This prism allows you to observe the refraction of light when a direct beam is shone through it. Perfect for science experiments. There are four different types, making it easy to compare how light refracts in each. You can teach optical theory through experimentation. Sizes: Square 60mm x 30mm, Concave 16mm x 60mm, Convex 16mm x 60mm, Right-angled isosceles triangle 60mm x 42.5mm