Inside of a latching relay is a pivoting magnetic strip or switch that is positioned between two coils. The electricity flowing into the coils generates a magnetic field. The switch reacts to the magnetic field, falling to one side or the other, resulting in either activating or deactivating the relay.
Once the magnetic field pushes the switch into either position, it remains there until another magnetic field arriving from the opposite direction pushes the switch to the other side. The benefit provided by latching relays is the ability to leave a switch in a position without using any power to do so. These relays are commonly found in remote lighting control, power supply and avionics applications..