3. Small Hole In The Window Of Plane

Airplane windows are made up of two pieces of perspex, which is plastic glass. Without the tiny hole in the window, the inner piece of glass would shatter due to the difference in pressure between the plane’s cabin and the outside.

The tiny hole lets air move from the cabin into the other pane of glass. The small hole equalizes the pressure between the two panes, it’s what keeps the cabin of the plane safe for such a tiny little detail. It has a huge life saving purpose.