ARPAT

From Airsoft Community Wiki

ARPAT (ARmy PATtern)

This is the official name for the camouflage design often described as ACU. (see ACU for more on the uniform itself)

ARPAT is a digitised design that, while not intended to hide the user from being seen in the usual manner of blended colours, is supposed to make it harder for the enemy to judge the distance to the target. This is achieved due to the fact that the digital pattern of the material is supposed to confuse the eye of the enemy making it harder to get an accurate idea of size/shape of the target hence rendering distance judgement unreliable.

It is particularly effective in the arid dusty regions of the world for which it was primarily designed. It however slightly less effective in temperate regions.