Oil quick drain - why did I order these gaskets?

[Flying Scotsman]

I ordered the Saf-air P5000 oil quick drain from ACS. The note next to it says:


Requires 2 each of P/N 05-02571 & 05-02572 for install

and those parts are listed below, so I ordered those, as well. But...for the life of me, and maybe I'm missing something patently obvious, I can't figure out what for! They're two smallish o-rings that look like the ones that I can see already installed...what the?

[Removed bit about other gasket...being totally dense tonight, I didn't realize it's *pipe thread* and therefore has no gasket...DOH!]

TIA and I apologize for my denseness...

Steve