In tinkering with hopes of somehow allowing my trunk to close a bit further into the car body to better align with tails lights, I found these. Both plastic caps come off with a decent amount of twist effort. I thought they were to adjust the amount of trunk surface that would lower into the car's body; i.e. twist to raise or lower trunk travel distance. But it appears that is not what they are for. One has the lose, silver nut that was just lying next to the screw stem. How it had not fallen into the bottom of the car is beyond me. Just what are these and what may they be used for?