It was 2002, and soccer superstar David Beckham was, for the first time, leading England into the World Cup as team captain. At each match he wore a different pair of personalized, champagne-colored cleats, embroidered with his children’s names on the red fold-over tongue. Though England lost in the quarterfinals, Beckham, and his shoes, went on to lasting fame, landing a $160.8 million lifetime deal with Adidas the following year.

For all the adulation Beckham inspired in his fans, animal-rights activists had an equal amount of anger: His iconic Predators were made of kangaroo leather.

Described as soft and flexible yet very strong, “k-leather” is used for soccer cleats by many companies, including Adidas, Nike, and Puma. For several years leading