Jonathan Morris wrote:
Mike Barnes wrote:
That seems rather inflexible. I'd have a sticker on the diffuser showing
the proper sign. And, for good measure, which way it should face. :-)

In the case of a keep left/keep right sign, it must be possible to have
a swappable sign that's fitted in a 'window' at the top and secured in
place somehow, to prevent kids playing around with it.


Hmm - "secured in place somehow, to prevent kids playing around with
it" - perhaps the ultimate technical challenge of our time!