These are primarily used by the boating community.
Nobody realizes yet that they would make great arson weapons.
If you have your own 12 gauge shotgun, you can launch them through it.
If you have a handfull you could set an entire forest or neighborhood quickly on fire.
But like I said, these are primarily used by the boating community. I used to race yachts from Saint Francis Yacht Clubhouse to Monterey, and we always had one set onboard with us. BTW that's where The Americas Cup is now on display, thanks to Larry Ellison.
Anyone can buy them and possess them, however it is illegal to launch one over dry land.