Anti-Terror fashion accessory

I'm going to London in the middle of September for three reasons:

1) family reunion,
2) to escape the upcoming election campaign, and
3) adventure tourism (riding the tube).

To the left is a picture that my brother sent me of the latest must-have for tube travel. Although it's explicitly marketed for Asians, I'm only slightly whiter than the unfortunate Jean Charles de Menezes and so it would still be a good thing to have.