These UV-sensitive beads contain a pigment which changes color when exposed to ultraviolet light from the Sun or other UV source. The pony beads are not, however, affected by visible light and so will remain white indoors, or when shielded from UV light as is the case in most modern automobiles. Many of today's space telescopes observe colors of light not in the visible spectrum such as infrared and ultraviolet. Children can make a simple bracelet from a standard pipe cleaner or strip of rawhide which can function as a UV detector. Many other experiments are possible as well... test sunglasses for the effectiveness of their UV protection, or even suntan lotion. We have only just begun to discover the possibilities! Available in five colors, all beads are off-white in the absence of UV light. The beads will cycle back and forth (white to colored to white) over 50, 000 times