Given that it reflects light back in the same direction as it comes in, I’d guess it’s based on the same principle as the 3M retro-reflective material (Scotchli

Given that it reflects light back in the same direction as it comes in, I’d guess it’s based on the same principle as the 3M retro-reflective material (Scotchlite). Presumably it’s a suspension of either spherical beads or tiny corner reflectors (quartz crystals?).