This beaker, with no markings, bends light the same as cooking oil. The borosilicate glass and the oil have roughly the same index of refraction. When this beaker is immersed into a container of oil, the beaker becomes invisible. Package includes the beaker and instructions. You supply the outer container which can be any clear, colorless container with at least a 4" opening.Drop pieces of broken borosilicate glass into a large container of oil and watch the pieces disappear. Then, using tongs, reach in and remove a previously hidden, unbroken beaker. Ask students to explain. Give credit for Mass Hypnosis!