Why do I have fuses in the bed of my truck?

Took off the plastic bed liner the previous owner installed and saw these fuse boxes. I originally thaught they were for a trailer but there way to far from the trailer hitch. So what are they for?

 

Topper shell hook up for brake lights....

 

Camper shell. I have them in mine with my shell.

 

That's my guess as well. Trace the wires and see where they go. One was probably the 3rd brake light, so it will mostly be tapped into the tail light and the other I would guess goes to the battery for lights in the shell. That's how my shell is wired.

 

Im thinking one goes to the brake wire and the other goes to the parking lights for the interior light thats the way most of them are wired....

 

Pretty much. Ill check mind. My interior light is battery operated but it my harness was put in for my break light etc.