If you're familiar with AT Overland, you'll recognize right away that it's based on the company's Aterra XL flatbed truck camper (in which the camper completely replaces the truck bed).

AT Overland Aterra Slide-In: Availability & Pricing Initially, the ASI is available for full-size trucks with bed lengths of 5.5, 6.5, 6.75, and 8 feet.