Conservation Clear® Acrylic UV Blocking Diagram shows how 99% of harmful UV light is blocked. The UV is blocked by conservation grade protection built into the acrylic substrate. This permits 99% blockage of harmful UV light, while transmitting 92% of the light. This acrylic is conservation grade and protects objects inside the frame against irreversible UV light damage. The dangers associated with harmful UV light exist both indoors from artificial light and outdoors from natural light. And this acrylic will protect against it.