The scrim scarf is a loosely woven piece of cloth that has been in service with Commonwealth armies since the Second World War. It serves a number of purposes, normally it is worn loosely round the neck to help prevent the neck from chafing on the collar of your uniform, to act as a sweat rag and as a general purpose scarf. However it has another more martial purpose as it can be worn draped over the head and helmet as a layer of camouflage, concealing the light colour of the face and breaking up its outline. Its loose weave still allows the wearer to see and fire his weapon easily, but makes him much more concealable. During the Second World War scrim scarves with blotches of dark green and brown camouflage were issued, however today we are looking at a modern Australian Army example:

The colour of this scarf picks up the base colour of the Auscam uniform and is a yellowy green colour that has been chosen to blend in well with the Australian bush. Spread out the loose, net like weave of the scarf can be clearly seen:

These scarves were very popular in the British Army right through the cold war, but in recent conflicts their popularity has waned in favour of the shemagh, I am less clear how widespread their use was with the Australian Army, although this example was given me by an Australian Army veteran so they were certainly used to some extent.