With the help of 1.2 million foot scans, we updated Ultraboost with a complete 360 female fit improvement. And we didn't stop there. We re-engineered the rubber outsole. We tested hundreds of prototypes. We kept going until we saw visible improvements in performance. The result? 4% more forefoot energy return, compared to Ultraboost 21 for women. The adidas PRIMEKNIT upper includes a narrower heel fit, designed to avoid heel slip and blisters. You'll be riding on a BOOST midsole with a Linear Energy Push system. This product is made with a yarn that features 50% recycled polyester and 50% Parley Ocean Plastic - plastic waste which we intercepted from remote islands, beaches, coastal communities and shorelines in order to prevent it from polluting our oceans. In total, this product has 20% recycled content.