National Distinguishing Sign Patch
The Australian Flag patch is known as the National Distinguishing Sign patch and is authorised in High Vis and Low Vis options.
The following extract from the Army Dress Manual provides guidance on wear.
The National Distinguishing Sign is an embroidered insignia in the form of the ANF with the word ‘AUSTRALIA’ below. This insignia is as follows
The high visibility sign distinguishing–ANF is worn in barracks by all personnel wearing General Duty Dress (AMCU). The high visibility sign is worn on the velcro patch on the left sleeve under the Australian Army Rising Sun Badge. The Red Cross (Geneva Convention requirements) patch is the exception and is to be worn on a brassard under the national distinguishing sign on the left sleeve. The high visibility sign distinguishing–ANF and Red Cross are not to be sewn onto the left sleeve of the AMCU shirt.
The low visibility sign distinguishing–ANF is worn in the field or on operations by all personnel with Field Dress (AMCU) and Combat Dress (AMCU). It is worn on the velcro patch on the left sleeve under the Australian Army Rising Sun Badge. The Red Cross (Geneva Convention requirements) patch is the exception and is to be worn on a brassard under the national distinguishing sign on the left sleeve, IAW paragraph 3.90. The low visibility sign distinguishing–ANF and Red Cross are not to be sewn onto the left sleeve of the AMCU shirt.
These can be purchased individually or in bulk here;