Temporal displacement weapon

A temporal displacement weapon was a type of firearm that displaced the person or object it was fired at to the time the user set it to.

Krasko had one and planned to displace Rosa Parks in time, but found his neural implant prevented him from doing so. He then started to use it to stop Rosa from getting on the relevant bus and eventually refusing to give up her seat, by changing small events that would eventually stop her from doing so. (TV: Rosa)