 Complete the following phrase:  Hamilton has also used one-off helmet designs to pay tribute to influential figures in his career. At the 2011 Brazilian Grand Prix, he wore a special helmet in tribute to Ayrton Senna which was auctioned after the race in aid of the Ayrton Senna Foundation. At the 2019 Monaco Grand Prix, Hamilton, like fellow driver Sebastian Vettel, wore a special helmet to pay tribute to Niki Lauda, who died at the start of the week. The helmet was painted red and white, Laudas classic colours, and had his name printed on the back. After the race, Hamilton reflected on Laudas career, saying: Ultimately, as a driver, my goal one day is to hopefully be as respected as he was ... Hes definitely someone who led by a great example, left a great example, and was a real hero to so many. Hamilton again wore a special helmet to pay tribute to Ayrton Senna at the 