Crystal Pendulum. Pendulum dowsing is an ancient art of accessing information not available to us through the use of our senses.

One could classify pendulums according to their intended use, e.g. pendulums used for healing specific illnesses, pendulums for adjusting chakras, teleradiesthesia (distance healing, map dowsing), etc. Or just ask to be shown a pendulum response for "yes" and "no".