One door-bell Ding later

We now have two fire extinguishers with agents that extinguish fires of classes A, B, and C. Honestly I didn't know (three days ago, an hour before finalizing my extinguisher order) that there are different extinguishing agents for different fire classes. I didn't even properly know that there are fire classes. I mean, I knew that there's a sciencey art to fires; I knew there are specialists who determine how arsonists light fires and whatnot. I also knew that one should check one's extinguishers periodically to see if they are still good. What I didn't know was that I could naively have bought a limited-use extinguisher that would put out a fire kindled by a napkin but not put on a fire fed by gas. But don't worry, I didn't buy any such thing. I bought two non-dinky fire extinguishers.
   It seems odd that by law you have to have fire detectors in your house when you sell it, but not fire extinguishers.