He makes limited public appearances and hasn't fought in 33 years, but a new endorsement deal with Under Armour attests to the sustained legacy of the world's most famous boxer, Muhammad Ali.

Under Armour and Ali on Wednesday announced a partnership in which the Baltimore-based company will produce lifestyle and training apparel inspired by the cultural icon.

Both Ali and Under Armour posted a 15-second promotional video to their Twitter accounts:

Ali is a heavyweight champion and Olympic gold medalist whose personality transcended boxing. He was an outsize personality who was never afraid to voice his opinion and famously refused to serve in the Vietnam War. In 1984 Ali was diagnosed with Parkinson's Syndrome and while he lives a mostly private life, he is still idolized by many. He's got 477,000 followers and Twitter and is considered one of the most recognizable athletes ever.

"He's an iconic hero from the past and a true innovator," said Glenn Silbert, vice president of men's, outdoors and team sports for Under Armour. "We wondered what Ali would have been like if he had a brand like ours when he was getting started and how great it could have been. That has been the mentality of our design team throughout this process."

According to ESPN, the partnership is officially between Under Armour and Authentic Brands Group (ABG), which bought Ali's estate and licensing rights in 2013. ABG owns the trademarks to a slew of phrases related to Ali, including, "Float Like A Butterfly Sting Like A Bee," "The Greatest Of All Time" and "Rumble In The Jungle."

Under Armour will launch Ali's apparel line in March and training line in November.

"Under Armour is irreverent, disruptive, they pivot quickly and they're explosive," said Nick Woodhouse, president and chief marketing officer of ABG. "Those words also speak to Ali and how he changed the game."

Under Armour has been selective in how many athletes it signs for endorsement deals with Tom Brady and Stephen Curry being among the notable choices. It also has taken an innovative approach toward the women's market with campaigns featuring Misty Copeland of the American Ballet Theatre and supermodel Gisele.

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