The aerodynamic RT Series truck cap features a 54-in. rear door height that is suited for hauling bulky items such as building materials or heavy powersports vehicles.

The SpaceKap truck cap, manufactured by Fibrocap Inc., is a self-contained mobile unit constructed of double-sided fiberglass walls with a reinforced floor and stainless steel hardware.

So you were driving behind a semi truck in slow traffic the other day and noticed something peculiar at the top of its tall ...