On Jun 17, 11:20*pm, Adrian C wrote:
Take a look at this pic

http://upload.wikimedia.org/wikipedia/commons/b/ba/London_Bus_route_2...

Central to that side poster of an orange diver, there is a transparent
thing that looks like a socket or vent for something. What is its
purpose? Currently there is a poster campaign showing a girls face and
this thing as her jewellery nose stud!

--
Adrian C

The large advertising panels on the sides of buses can flex and bow
outwards and in certain circumstances the panel could pop out of the
frame. The 'stud' is there to stop the panel flexing.

Peter