Solved Robo R1 plus - extra parts(?)

I noticed these two rings laying near the right and left "riser rods" and wondering what they are? One ring was on the left side laying on the white plastic base and the other ring on the right side (meaning the side the on/off switch is on) near the riser rods also on the white plastic base. Any clue what they are and/or where they might have come from?

 

... that's what I thought. There like 10mm and 15mm inside diameters. The rods are like 8mm.