A flatbed with a lowered rear deck (about 3.5 feet off the ground vs. 5 feet standard), raising the legal height clearance for tall cargo. Used for construction equipment and oversized freight.
A step deck is functionally a flatbed with the rear deck lowered — about 3.5 feet off the ground instead of the standard 5 — which raises how tall a legal-height load can be before it needs an oversize permit. That extra clearance is the entire reason step decks exist: for cargo too tall for a standard flatbed but not tall enough to need the escort vehicles and permitting a true oversize load requires.