Fire Extinguisher for hot shot?

I have one in my car, mounted because if getting into a smash up it becomes a missile, just something that can fly when something happens and you know where them missiles are headed.

 

It must be mounted. Otherwise they’ll give you a ticket the first time they inspect your truck.

 

Any regulation on size or just particular preference? Also where do you mount yours?

 

I mounted mine inside. The drivers side rear door below my rear seat.

 

I was thinking back seat somewhere like fbc has it. Is there a stipulation about it being mounted inside or outside the cab? Such as in bed tool boxes or things of that nature?

 

Mount inside so it won't be stolen, I use the smallest one available 3 lbs unit look just like the one in the pic.