Abstract: A positive expiratory pressure device (PEP) has one or more of the following features, alone or in any combination: 1) a combination of oscillation PEP therapy and standard PEP therapy, 2) use of microwavable materials, 3) use of an oscillation rocker that produces a venturi effect, 4) use of a flexible tube to create the air pressure oscillation, 5) use of a rotating wheel to open and close the air channel and create air pressure oscillation, 6) use of a variable cross section air channel to generate different air flow resistance for providing multiple levels of constant pressure therapy, 7) use of a flexible air flow stopper plate with adjustable pivot point to generate different air flow resistance for providing multiple levels of constant pressure therapy, and 8) use of a selection switch that allows the device to switch between standard PEP therapy and oscillatory PEP therapy.