There's this plastic rectangle thing in the cargo area. What is this and what is its intended use?

(see yellow part in the image)


What is the yellow part in the image?

 

for what ever you want to use it for and if you don't like it you can remove it.

if you have some thing long that you don't rolling around then you can stand it up there.

if you have dogs you can tie their leash their so they are not moving around.

if you carrying something that moves back there you can use it that to tie it down.

 

I keep a basic first aid kit and some tools in a bag under it. I also keep some stuff around the spare tire, but that's much harder to get to if you have stuff in the back.