Need input on oil filter on '85 535

I have a 1985 535 BMW and I'd appreciate some insight on installing the
new cartridge oil filter. I'm fairly adept in this sort of thing but my
mechanics instructions for all the parts that came with the filter don't
seem to match what the previous filter had. The new German paper filter
came with:

- 3 aluminum washers 2 small, and one large, approx 1" diameter
- 1 large O-ring ~4" in diameter and one very small O-ring ~1/4" in
diameter.

My mechanic told me to use both small washers and both O-rings and ignore
the large washer. I understand to use the large O-ring for the housing, 1
small washer for the bolt as it enters the cartridge casing but what is
the 2nd washer for and the tiny O-ring?

Bentley or Chilton manuals don't seem to have this level of detail.

Any help is appreciated.
Dan