Hi,

There's nothing wrong with the temperature extremes. They are fire extinguishers anyway, which means the hottest weather available. They are very over engineered. The sub zero part is also irrelevant, because most of the materials used (plastic, metal) will not be brittle till ~50 (I love to answer metric questions... <img src="/images/graemlins/laugh.gif" alt="" /> ). Maybe the seal would suffer.

You should be aware to keep the -generally- yearly inspection dates.

The other thing to consider is the place and fixation of the unit. Many cars have factory built in points under the front seats, and these can acccept the optional cradle. (It will cost you a fortune, but only the genuine set will provide proper collision protection.) If you dont't have the possibility to place the extinguisher here, then it should be in the trunk. In case of minivans, SUVs, wagons, etc. where the passanger compartment is not physically divided from the trunk, the unit must be secured with very strong quick release latches, or the like. (Never forget, that a fire extinguisher is technically the biggest full metal jacket bullet, if it rides through the cabin.)

Best,

Zerge