When doing lens fitting on the wing, it is recommended to pre-drill or make a small deep mark using the wing rivet holes (upper or lower) as a guide and finish drilling outside the wing before fully drilling the lens, you should use a bank of screws to hold the lens. and drill with low RPM and VERY little pressure. This to avoid misalignment or cracking by holding the lens with tape alone. Note: You need to hold a piece of wood under the lens while drilling the Plexiglass and do the drilling in 2 steps: first finish drilling the top holes, reposition the lens on the wing and repeat the procedure with the remaining holes.