Envelop X-Ray Spray turns opaque paper temporarily, allowing the user to view the contents of an envelop without ever opening it. 30 seconds after the application, the envelop will return to its original state, leaving absolutely no markings, discoloration; or other indications of use. Each can treats several hundred square inches. Non-flammable, non-conductive, and non-photochemical reactive. Environmentally-friendly (contains no Freon).
WARNING: Not to be used on U.S. Mail, except by, or with the express permission of, the addressee. Not shippable by Air.