Flexibility of traffic control and installation is offered by the 4900 Series Deadlatches. A reverse turn of the key while bolt is held retracted retains the bolt to allow two-way traffic for applications which require free entrance at certain times and exit-only at other times. Interchangeable without stile modification with any MS1850A or MS1850S deadbolt of same backset and faceplate shape. Also retrofits to existing 4500/4700 Deadlatch preparations. Steel case with corrosion-resistant plating....