The 3900 series mortice nightlatches from Gainsborough Hardware functions as primary locks, and communicating and exit nightlatches.
The mortice locks feature a latchbolt that is retracted by a series of cylinders and turnbuttons. The deadlatching nightlatch series have a no handle mechanism–each latching function is deadlatched by an auxiliary bolt on closure of the door.
The latchbolt comes in 14mm sintered stainless steel and 60mm backsets are available for the mortice locks.
Cylinders are oval type used in Australian mortice locks and can be interchanged with other specially keyed cylinders.
The 3900 series mortice nightlatches feature the cylinder below the knob handle for ease of operation and convenience.