Accentra Steel Mullions

An Accentra (formerly known as Yale) steel mullion is a steel vertical element used to divide sections of a door, often used to adapt a double door into two single doors. It provides structural support and is made steel. Mullions are distinct from muntins, which divide glass panes within a window sash. 

These are specifically designed for use with Yale's 1800, 2100, 6000, and 7100 series exit devices. They are often tubular steel, 2" x 3" in size, and may be field-cut to fit specific openings. They can also be fire-rated (rated to withstand fire for a specific period of time).