Equilateral prisms, 1" sides and 1, 2, & 4" lengths. Made of transparent acrylic so they won't break if dropped.
A prism is a transparent optical element with flat, polished surfaces that refract light. At least two of the flat surfaces must have an angle between them. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides.