Help with Mysterious Part, M18 Quiklok

I just bought the Milwaukee Quiklok String Trimmer attachment.
There is a 4” unthreaded rod in the bag with the screws that fasten the String Guard to the shaft.
I can not find any info on this in the manual or online.
I am hoping somebody here might be able to tell me what it is for ?
You can see it in this picture, with the 4 screws for the guard.
Thanks in advance.

Maybe the parts diagram may help:


Thanks. I had already looked at that, and looked again.
I can’t find the piece in any of the schematics or photos.
I could be missing it, but you’d think that Milwaukee would give some clue to its purpose. Assuming there is a purpose.
If nothing else, looking at the schematics is a reminder how far we have come from simple hand-made tools.

Hi there Fred, I was also looking something similar in that diagram pdf but couldn’t find it. Definitely following this, need a trustable source to search all of this. Please, someone share it here if they are aware.

Looking at Page 3 of the PDF:

Its shape looks like part of #101 (the string trimmer guard) which comes with 4 x M6x14mm screws (#66)
Maybe your black piece is some sort of replacement for the trimmer guard (to be used in tight spots??) - to be attached with the screws provided. The pin (who knows - to help align things??) - anyway just a wild-ass guess.

I asked our super-awesome Milwaukee contact, and they provided the following advisement:

The 4 screws are for attaching the guard. The rod is used to lock the trimmer head in place so that it can be removed/replaced. Hope that helps!

Thank you, all.
The manual for the Easy Load Trimmer Head shows the rod and how to use it.

Milwaukee Easy Load Trimmer Manual

Here is a photo from a review.