The rear frame is made of high-strength, tubular steel. The rear header to top rail connection is reinforced at the corners by massive .25" steel gussets, both top and side, which minimize racking and ensure that the frame remains square throughout the life of the trailer. Because the rear header does not protrude into the door opening the Composite maintains a full 110" inside height the full length of the trailer.

The rear frame is further strengthened by an integral bottom rail to rear frame reinforcing gusset, which distributes the stresses of dock impact.

Two lock rods per door provide added strength and security. An additional safety feature, the Secure-Cam is standard on the curbside door allowing the lock rod to be secured with a padlock directly to the lower keeper.