Tommie Smith was honored recently at a benefit concert in Brooklyn for criminal justice reform 50 years after he and fellow U.S. athlete John Carlos focused international attention on racism with a protest during a ceremony at the 1968 Olympics in Mexico City.

Smith and Carlos, gold and bronze medalists respectively in the 200-meter sprint, powerfully bowed their heads and raised their fists after receiving their awards and as the U.S. national anthem played.

The Olympians both raised one single black-gloved fist to protest oppression and racism as they had their moment on the world stage on Oct. 16, 1968. They also stood shoeless on the podium, to represent a fight against poverty.

Smith and Carlos’ raised fists have continued to serve as an iconic symbol for the fight for equality and human rights.

As soon as we raised our hands, it’s like somebody hit a switch,” Carlos wrote in an article for Vox in 2016. “The mood in the stadium went straight to venom.”

Filmmaker Ava DuVernay introduced Smith at the fourth annual benefit concert on Tuesday put on by Tidal, a music streaming service and sponsored by several other organizations.

“Upon returning home, (Smith and Carlos) were called traitors and much, much worse by most of America,” Duvernay said. “They and their families lived under the threat of daily violence or death; rather than returning home as conquering heroes, they became social pariah.”

She added, “It’s difficult to estimate how many minds were changed that day they raised their fists in protests, or the days, the months, the weeks, the years, the five decades that have followed.”

DuVernay also took note of Australian Peter Norman, the silver medalist in the sprint who stood alongside Smith and Carlos on the podium wearing an Olympic Project for Human Rights button in solidarity of their protest. Norman died in 2006.

Colin Kaepernick, the former San Francisco 49ers NFL quarterback who two years ago instigated protests at NFL games by players, earlier this month paid tribute to Carlos and Smith on Twitter.

“They have laid the foundation [for] the advancement of many others at their own personal expense,” he wrote.

Kaepernick, who completed his $1 million dollar pledge to underserved communities early this year, powerfully sat and later kneeled during the national anthem at football games to protest police brutality and racial injustices. Players on his own team and several others have periodically continued those protests.

The benefit concert, Tidal X: Brooklyn, included performances by Lauryn Hill, Lil Wayne, Nick Jonas, Meek Mill, Black Thought, Teyana Taylor and Anderson .Paak.

All of the show’s net ticket proceeds, as well as donations, will support criminal justice reform non-profit organizations, including #Cut50, Equal Justice Initiative and the Innocence Project, according to event organizers.

A short video featuring Smith, Carlos and Norman at the 1968 medal ceremony played before DuVernay introduced Smith at the show. He walked on stage with his fist raised in the air.

“Equality… we cannot do without it,” he told the crowd. “We all have a responsibility” to work toward that goal.