High security cylinder mortice locks and latches providing the latest in design and functionality. Suitable for heavy duty use in industrial and commercial buildings, institutions, clubs, schools, hospitals, hotels and similar buildings. Various latching functions operated by a key outside and by a turnknob or key inside. The nightlatch locks automatically when the door is closed. Nightlatch functions are suitable for applications such as switchboards, risers, cupboards and gates. For all nightlatch functions specify the primary lock (3P70SS). This lock can be easily adapted to suit function required whilst the mortice lock is installed in the door.