The first pairs of the famous self-lacing MAG shoes from "Back to the Future II" will be made available this month to the public, but you won't be able to buy them.

You'll have to win them.

Nike announced that only 89 pairs will be available through an online draw that begins Tuesday and ends a week later. Winners will be informed on Oct. 17. Entries to the raffle are $10 each, with the proceeds going to the Michael J. Fox Foundation to fight for a cure to Parkinson's disease. Four additional pairs will be auctioned off in Hong Kong, London and New York during the next five weeks.

Nike raffle for 86 pairs of self-lacing MAG shoes raised $6.75 million for Parkinson's research. Courtesy Nike

Nike recently developed the technology to have laces wrap around the foot to give it that perfectly snug feel. A running shoe called the HyperAdapt 1.0 will be sold in November.

On Oct. 21, 2015, the very day Michael J. Fox's Marty McFly traveled to in the 1989 film, Nike presented him with a working, self-lacing Air MAG pair of shoes.

"Though it initially shared only a few seconds of screen time with Michael, the idea behind the Nike Mag unlocked something much bigger at Nike," Nike CEO and president Mark Parker said in a statement. "It sent us down an uncharted path of innovation, but it also opened our eyes to our ability to fight some of the world's biggest challenges. We feel privileged for the opportunity to raise even more awareness for the fight against Parkinson's."

In 2011, Nike raised $5.7 million for the foundation by auctioning 1,500 pairs of Air MAGS that didn't self-lace.