The Men in Black neuralyzer toy is a replica of the neuralyzer used by the agents in the movie by the same name. The toy is made from plastic with several fake buttons and switches that purportedly allows the user to "erase" the memory of bystanders during alien encounters with the Men in Black.
In the movie, the neuralyzer is used by the Men in Black to emit a bright flash that erases the memories of those who see it. The Men in Black put on sunglasses while using it so as not to affect their own memories. After neurlyzing a person, the agents then replace the erased memories with new ones within 30 seconds.