ye those are the type i have on car, i don't have the washers. i honestly after 3 2nd gens have not seen those, . even on ones i worked on back in the day. learned something new. thanks i believe the shoulder is so the lens hopefully would not get cracked from over tightening the screws, the washer would help in that case also. hmm might have to get some of those.Correct screws for the lenses….note plastic beveled washer.