Need Help What is this small plug for?

[Red Fazer]

After exchanging a cable for trickle charging that had stopped working, I noticed a small piece of rubber or silicone that had come loose. The cable was pulled through an opening at the front of the frame, on the right side. After a bit of research I think I found it may be a ”plug” with number 11 in the attached image.

I haven’t been able to put it back yet and wonder if anyone knows what it’s for and how important it is to put it back?

 

[Motogiro]

Yamaha includes spare emergency ear plugs with every bike...... Nahhh...... Those are frame vent plugs. It allows moisture to escape with temperature change to help prolong frame health. Point them downward....
No...don't stick those in your ears!