What does "4-section" or "5-section" mean for an electric boxspring?

The number of sections shows how many parts the sleeping surface of an electric boxspring can move in. On a 4-section model, such as the Elektrobox 23 or the Elektrobox Elite 23, you adjust the head and leg section separately. On a 5-section model, such as the Elektrobox Hercules Linear 25, there's an extra hinge for even finer control of your sleeping or sitting position, for example extra support in your lower back.