A common misconception is that ultraviolet light is purple in color—it's actually invisible! Demonstrate this fascinating concept visually with two plastic filters. One prevents the passage of UV light and the other allows it. When these filters are placed over a special UV fluorescent ink and then under an ultraviolet light, a message appears under the one of the filters, but not the other. Filters can be used to show the fluorescence of many other items too! U.S. currency with special fluorescent stripes, bright white photocopy paper treated with special pigments, laundry detergents, UV detection beads, and much more. You can also use the yellow card to test windows, eye glasses, and safety glasses for their ability to filter UV light. The possibilities are endless with this affordable, fun demonstration! Set includes detailed instructions with activity suggestions, yellow card printed with UV sensitive ink, and two plastic filters, 2¾" diameter.