Great addition to tama chairs! It becomes really comfortable, unloads the back! the only negative, with a back, it is not very convenient to sit on round chairs, because in order to rest your back on round chairs, you have to sit deeper, not in the center of the chair, because of this, the legs become uncomfortable, and the hips rest against the chair! The most optimal solution, installation of the backrest on chairs of the Ergo rider series and moto saddles!