In contrast to the Expand-a-lung device, the Breather and Breather Fit allow you to independently increase or adjust the training intensity for inspiratory and expiratory muscles.
This is important as your inspiratory muscles, especially your diaphragm, gain strength much quicker than your expiratory muscles. Furthermore, the mouthpiece of the Breather and Breather Fit are ergonomically designed to not put undue pressure on the jaw.