From The Truth About Guns:

To qualify, a person or company must have had its AdWords/AdSense account suspended or terminated by Google LLC between March 2014 and September 2017 based on the fact their websites advertised “any products that (i) were designed to injure an opponent in sport, self-defense or combat such as knives, crossbows and guns or (ii) which comprised any part or component necessary to the function of a gun (iii) or which were intended for attachment to a gun” in violation of Google’s “dangerous products or services policy.”