Good reminder. Thanks for posting. I have two, the original small one and one I bought that is about the size of a big can of beer. (As someone stated). If it were not so danged cold today I would right out and look at them. Hopefully someone will post a thread to remind me in the spring.
I also heard that with the dry chemical ones you should remove them from their mount and bang on the bottom of them with your hand once a year. Apparently all that bouncing going down the road causes the chemical in them to get hard and stick to the bottom of the extinguisher.