From the hub: discussion of the super-phone presented by CATerpillar (the rubber aluminum body, dust-resistant, can withstand underwater at a depth of a meter for half an hour and does not thunder).

Sicness
Sorry for not much of the off-topic and nubic question, but what is the reason for the permissible time in the water? Why half an hour?

Shultc
He can hold his breath for no more than half an hour. Then he breathes and begins to squeeze.

by las68
In half an hour, the bulldozer must get out of the drowned tractor, and call the master of the site, and if he did not get out - why does he have a smartphone?