A:Answer Bestbuy won't let me edit my other answer, which is wrong. I stated in the answer that it might be incorrect.
The Correct answer is "COLOR" the dash followed by a w or b means "Black" or "White", and the W.aus is white & silver. There is B.aus as well, and I am guessing its black & silver, but you'll have to double check that one.
The reason this was difficult for some people to figure out is because the websites where the products are sold use a single picture for multiple colors. Often times they use photos of different monitors (usually a similar model, but not exactly the same) as well.
2BH their lazy, and if it dups you into spending money on somthing you didn't want to, its a win for them because you just bought their product, even if you return it, it helps their data look better in the short run.
Its very important to do full research on products before engaging in a transaction.