A prefabricated flashing product for an opening in an exterior surface of a structure includes a generally planar flange shaped to conform to the exterior surface, the flange extending outwardly from an entire perimeter of an aperture therein that corresponds to the opening, and a return that seals to the flange about the aperture and extends substantially perpendicularly therefrom toward an inward direction of the opening. The flange and the return are monolithically formed of a waterproof material. A method of integrating a fenestration product into an opening of an exterior surface of a structure includes inserting the flashing product described above into the opening, and inserting the fenestration product at least partially into the aperture of the flashing product.