Memory wiping devices used by the agents in the Men in Black series. Simply change the dials for how far back you want someone to forget, give them a flash, and the device "will isolate the electronic impulses in your brains and more specifically the ones for memory."
A neuralyzer uses sends out a special electronic impulse that causes, effectively, a form of hypnosis. When someone looks at an activated neuralyzer, they are prone to the suggestions of the user. This is more effective in erasing memories, but it can also be used to implant suggestions, though it isn't guaranteed the person will act on it. For example, after neuralyzing a former partner, Agent J suggested he go find someone to start a family with, which is exactly what the man did. However, if he puts this suggestion in the head of someone who didn't already want it, nothing would happen.
The memory erasing effects of the device, though, work 100% of the time no matter who it is used on. The time span erased is controlled by dials on the neuralyzer. The person using it tends to put in a few details so as to prevent the person being neuralyzed from being to disoriented.
The information used to make neuralyzers was traded to the Men in Black by some aliens. When originally used in the 60s, the neuralyzer was a giant contraption involving a complex laser system that was impossible to transport. A more advanced model could be carried by an ordinary person and even concealed in bulky clothing, but it needed a special battery pack that used a dial-up connection similar to the early forms of the internet. The modern form of the device is smaller (only about a foot long) and can be operated without any additional equipment.