Last summer Adidas prototyped a shoe constructed from plastic waste and old fishing nets found drifting in the ocean. But there was a major flaw. The sneaker was incredibly stiff, rendering it nearly impossible to wear, let alone walk or run in. This week, however, the German company unveiled a much-improved version of the shoe.

The new Adidas x Parley was designed with Parley for the Oceans, an initiative that unites top minds to address the major threats to our biggest ecosystem. And in honor of World Oceans Day on June 8, Adidas has released a limited number of the eco-friendly shoes, whose upper portion is made entirely of recycled plastic. But if you want a pair, you’ll need to get creative. People from around the world have until the end of July to post an Instagram video showing how they plan to avoid single-use plastic items. The 50 winners will each receive one pair of Adidas x Parley. The competition is being promoted by some of the biggest names in sports, including the retired French soccer player Zinedine Zidane, who is sponsored by Adidas and is a supporter of Parley for the Oceans.

A close-up shows the finely spun plastics on the upper half of the shoe.

Although Adidas is releasing just 50 pairs this summer, there is reason to believe it will create many more versions. Not only has the company invested heavily in eco-friendly measures , but so far this year Parley has intercepted a total of 746 tons of marine debris, which included 379 tons of plastic waste from coastlines, beaches, reefs, and high seas.