An M-80 is a GBFC (great big firecracker). As I understand it, an M-80 is roughly the equivalent to half a stick of dynamite. Great Big Loud Band. Lots of shock waves. My nephew once used his car battery to set one off under an upturned 5 gallon bucket. What was left of the buck went clean out of sight. I was sitting on the front porch about 100 feet away and could feel the shock waves pressing against my chest.