American Educational 7 Piece Acrylic Lens and Prism SetSet of seven lenses and prisms for demonstrating optical principles and effects for students Includes double concave, double convex, trapezoidal, plano convex, and various triangular shaped lenses Made of acrylic for optical clarity The American Educational 7 Piece Acrylic Lens and Prism Set has lenses of different shapes for demonstrating optical principles and effects for students. The set includes double concave, double convex, trapezoidal, plano