3 piece Equilateral Prism set. Includes 20mm, 50mm and 100mm sizes, each with 25mm faces. Made of durable, highly polished acrylic. Excellent tool for optical experiments, and can be used for photography lighting effects as well. Prisms will create a nice rainbow (even in room light) by using the simple led light of a smart phone. User will need to create a small slit in a black piece of paper and use that slit in front of the led which will create a light ray. The prisms will then refract the white light and create a nice rainbow on a target away from the prism. The farther away you move the target the bigger the rainbow gets and the more distinct colors the user can see. A great tool for teaching optics or for just having fun.