AirFly Duo is a wireless headphone adapter that lets you use your favorite wireless headphones or earbuds in places that only have a headphone jack – like airplanes and treadmills. Plug this tiny transmitter into a headphone jack to listen in-flight movies or the TVs at the gym. AirFly Duo lets two people listen to the same soundtrack, podcast or music with their favorite noise-cancelling headphones or AirPods.