The Duo Adapter Attachment allows you to use any recommended set of two Theragun attachments at once to treat more of the body with Theragun percussive therapy in half the time. With an innovative design that optimally positions both closed-cell foam attachments to contour to the different shapes and curves of the body, the Duo creates unique ways to treat specific areas, ailments, and more. Only compatible with Theragun Pro, Elite, Prime, and Mini. Please note, the Duo is not compatible with Large Ball attachment.