(Via one of my Intertubz Spy Network)
They sell it as a trajectory identification aide. BS. It’s for making nighttime at the range look like a Star Wars battle scene.
The plus about this particular brand is that it’s “cold”–it’s no more likely than standard ammo to set something on fire. It’s imperfect–you can’t see it in daylight–but on a heavily overcast day, or at an indoor range, you’re going to be able to identify whatever shooting problem ails you–in 9mm or .45 ACP, at any rate.