This is Vol. 16, 18, 19, 20, and 21 of the High-Speed Listening CD series. With so many app-based subscription materials available now, I think these CD types are convenient because they are easy to listen to while traveling or in the car. CDs only. Operation has been confirmed. Two of the five CDs are unopened. I am also selling other Shichida method materials, so please take a look. Thank you for viewing.