The PEP therapy helps keep the airways open by positive resistance breathing. This positive pressure allows airflow to get beneath the areas of mucus obstruction and move the mucus toward the larger airways, where it can be coughed out. The PEP therapy can be done using Acapella PEP, Flutter Device or PEP Value. The Acapella combines high frequency Vibratory and positive expiratory pressure (PEP) into single PEP device. The acapella comes in Green High Flow at least 15 L/min of expiratory flow and Blue less than 15 L/min of expiratory flow.