The item concerned is referred to as the “E-Flare Compact Safety and Emergency Beacon” (model # 939-AT280). This emergency beacon incorporates 8 LEDs, an ABS housing and a fresnel lens. It is powered by 4 AA batteries. The unit is waterproof up to 100 feet, dust proof, and will survive a 3 foot drop onto a concrete surface. The LEDs (visual signal) can be seen over ¾ mile away, with a maximum 360° visibility. The E-Flare easily attaches to belts, clothing, vehicles, traffic cones or signs. In use, the unit(s) would be placed around to create a highly visible warning and safety zone for people, work areas, hazards and accidents. Applications include use for traffic control, construction sites, rail yards/ports, and other safety applications.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N304814