The whistle.

Sao Paulo -  From these little shelter you can protect middle class houses. A water container to wash yourself outside and a brown container with drinking water inside. TV with a satellite receiver. A small kitchen with pans and other equipment. Cover the windows so you can hide yourself. Leave a space open in the middle so you can see the others. Left of the satellite receiver you find a whistle hanging on a small hook. Blow the whistle if you notice any danger. Brazilian way of making life easier. Sao Paulo 2 of December 2009 Lino Hellings
Lino Hellings – Sao Paulo Lab