Usually, the upper edge of the backrest should be about 10 cm below the armpit, about the width of the palm. The lower the backrest, the greater the range of motion of the upper part of the body and arms, and the more convenient the functional activities, but the support surface is small and affects the smoothness of the torso. Therefore, only disabled people with good balance and lighter impairment choose a wheelchair with a low backrest. Conversely, the higher the backrest, the larger the support surface, but it affects functional activities, so the height should be adjusted according to the person.