A device called the Active Denial System, or ADS and a Long-Range Acoustic Device, also known as the LRAD.
ADS is a weapon designed by the military that uses short radio waves that "provides a sensation of intense heat on the surface of the skin,” according to the written statements. This causes an intense burning feeling, leading to the tool also being called a "heat ray" or the "Pain Ray."
According to DeMarco, the email stated the lead military police officers were interested in the ADS as it could "immediately compel an individual to cease threatening behavior" and that the "effect is overwhelming, causing an immediate repel response by the targeted individual."
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Developed by the military as a crowd dispersal tool decades ago, the ADS has largely been abandoned amid doubt of its effectiveness and ethical questions.
The tool causes searing pain, but no actual physical damage.