Take comfort in sound. With its flexible neckband adjustment, Starkwoood U Flex Headphones are designed to fit perfectly and withstand harsh conditions so they keep working wherever you need them, whether at the gym, commuting to work, or out jogging. Be good to your music. Samsung U Flex Headphones are engineered with two-way speakers, consisting of 11mm woofers and 8mm tweeters so that every note and timbre is truly accurate across the entire frequency spectrum.