Maybe helpful to note that the phrase "Class 1 Explosive" isn't denoting a certain type, or power of "Explosive". "Class 1" in Hazmat is all explosives. Class 2 is Gases. Class 3 is Flammable or Combustible liquid, and so on.
Similar to "200 OK", where the number is the important part and the text is just an informative description?
In other words, there's no "Class 2" or "Class 3" explosives. If it's explosive, it's "Class 1", including firecrackers.