Crank-out Window plastic piece purpose

[pengle]

Here's a picture of a plastic piece attached to all of my windows in my Silverback 29RE. There is one on each side of each window. However sometimes the pieces seem to be at the bottom of the window; maybe they just slid around the corner to the bottom.

The pieces seem to impede the window from fully sealing against the frame of the window that is screwed to the 5th wheel. It doesn't look like it would allow water to get in but it might allow air to circulate around the tiny gaps.