The invention is related to anti-viral phosphinate compounds, compositions containing such compounds, and therapeutic methods that include the administration of such compounds, as well as to processes and intermediates useful for preparing such compounds. The optical assembly comprises a reflective image display that generates and reflects image light to an optically flat film then to a curved partially reflecting mirror of the optical assembly that reflects a portion of the image light from the image source and transmits a portion of the scene light from a see-through view of the surrounding environment to the user’s eye as a combined image. A first part that has first elongated holes for a screw fastening to the engine and openings for a screw fastening of a second bracket part.