These mountable, oversized acrylic lenses and prism help optimize classroom viewing of optics demonstrations on your whiteboard. The lenses (double convex, double concave, single convex, single concave, and semicircular) are about 8” L each, and the equilateral prism has 3” sides. The pre-attached magnetic backing allows ease of movement on the board. This 6-piece set comes in a sturdy wooden storage case and includes instructions.