A passthrough window is essential if want visibility through your camper or if you want access to your cab when you're inside your camper. The sliding 13”x13” opening makes it easy to pass small items through between your camper and cab. It also allows you to put a small amount of lumber in your camper/truck with it sticking out of the back of your tailgate. 

Note: The placement of this window is in the same position on all campers. Visibility may change depending on truck model. This option cannot be retrofitted to completed campers.