Light Crystal Acrylic Prism, 2.5"The Light Crystal is a highly polished piece of acrylic, ultra clear, in a prism shape that splits light beams and allows for interesting optical experiments and effects. We have a few prisms in our photo studio to create dappled light and faux reflections. They're also useful for learning about optics and color theory. Measures approx. 2. 5". Triangular prism in plastic storage box.