This is a training tool using trombone and tenor horn mouthpieces. It's a Flow Ball that you attach a mouthpiece to and blow to make the ball float. You can tell if air is being released by buzzing on the mouthpiece. Please refer to the details below for specifications. Although unused, it has been stored at home, so please understand this. https://www.thomann.de/be/astra_air_stream_trainer_trombone_s.htm Thank you very much. Please feel free to inquire about discounts for bulk purchases.