The trail fireworks is a weapon in the Fallout 76 update The Legendary Run.
Characteristics
A gold-colored clay pot containing black powder for a firework. When thrown, it impacts the target with no apparent effect, however, after a few seconds of delay, it releases four red trails of fireworks.
Locations
10 each are rewarded for reaching ranks 23 and 54 respectively during the Legendary Run.
Notes
Despite being labeled as a mine in the game files, the item behaves like a grenade.