Rubber sole BOOST midsole Imported Lace closure These Ultraboost running shoes serve up comfort and responsiveness. You'll be riding on a BOOST midsole for endless energy, with a Linear Energy Push system and a Continental Rubber outsole. This shoe's upper is made with a high-performance yarn which contains at least 50% Parley Ocean Plastic -reimagined plastic waste, intercepted on remote islands, beaches, coastal communities and shorelines, preventing it from polluting our ocean.