Fire extinguisher buy

If I may.... I'm just gonna give some friendly advise as I used to own a small fire protection equipment company.

The above is true. The little plastic ones like Kiddie are ok, but the extinguishers with plastic valves (or top) are cheaper but, do hold up better than they did 30 years ago when I was in the business. The inside truth about these are, they will expand & contract with the weather conditions or heat & cold. In all honesty, you wont have a huge temp difference with high or low inside the truck but, if your extinguisher is outside or in an outside compartment, this could be a problem.
If the plastic expands very much, it will cause the pressure inside the container to seep out around the "seat" inside the valve (or top) & your extinguisher wont be usable which will get you a ticket, besides throwing your money away on an inexpensive extinguisher... because, as stated above, you normally do not recharge those. Possibly some can, but as a rule they do not recharge those plastic ones. Get one with a steel valve (or top) & if you help someone put out their Mercedes, it can be recharged for about 1/3 or 1/2 the cost of a new one .... many times. As well, the ones with metal valves, normally do not expand/constrict & have a larger "seat" in them so they do not leak down very easily.

Just a helpful hint hope it helps. Good luck.