The Invisibility Booster is a device that Arthur Weasley installed in his flying car, the Ford Anglia. It is activated by pushing a button that on the dashboard which turns car invisible, including everyone in it.[1]
On their way to their second year at Hogwarts School of Witchcraft and Wizardry, Ronald Weasley and Harry Potter couldn't get through to the Hogwarts Express so they took the flying car to get to Hogwarts Castle from King's Cross Station. Unfortunately, the booster malfunctioned when they first started flying so they were spotted by several Muggles. It was reported in the newspapers. Arthur faced an investigation at work for illegally enchanting the car and driving it.[1]