Wikipedia
Neuralyzer
A neuralyzer, sometimes spelled as neuralizer, is a device seen in the Men in Black franchise. It is one of the signature tools and considered standard issue employed by the Men in Black. It is a device about the size of an average cigar tube that gives a bright flash which erases the memories of the past hours, days, weeks, months or years, depending on the chosen settings. It first appeared in the first issue of the comic book series, and has appeared in all three films, as well as the animated TV series.