We have developed 3 innovative lower-back exercise chairs with brand name "Duoro"(Duoro-01, Duoro-02, and Duoro-03). Duoro-01 is critical for its cute design and waist training function. As an office chair, Duoro-01 not only has basic functions like height adjustment and easy moving by casters but also has special exercise function for lower back. There needs no other tool like a motor to tremble user's waist. You can just sit on the chair and only circle your pelvis pushing your legs against the floor. You could feel hula-hooping sitting on the chair.