New South Wales Consolidated Regulations

ROAD RULES 2014 - REG 54

54 How to give a stop signal

(1) The driver of a vehicle must give a stop signal by means of the vehicle's brake lights.

(2) However, if the vehicle's brake lights are not in working order or are not clearly visible, or the vehicle is not fitted with brake lights, the driver must give the stop signal by giving a hand signal in accordance with rule 55, or using a mechanical signalling device fitted to the vehicle.

Note :
"Mechanical signalling device" is defined in the Dictionary.