Disposable barrier filter for pulmonary function testing x 50 Independent studies of the MicroGard filter clearly demonstrate that it acts as a barrier to viral and bacterial cross-contamination. Independent studies also demonstrated that MicroGard’s resistance to inspiratory and expiratory air flow is lower than published recommendations. There are now 3 varieties of MicroGard! MicroGard IIB with oval mouthpiece and assists patients with correct positioning of the teeth and lips (patent pending). And the MicroGard IIC with round mouthpiece for use in combination with separate mouthpiece. The MicroGard® II is the only filter that has gone through a full verification and validation process together with the medical equipment it is used on. Most filtration materials use surface loading as the primary means of removal. With the material used in the MicroGard® II product, the fibre matrix results in depth loading, where particles are captured throughout the entire filter material, not just on the surface. The filter material is composed of polymer fibers that will not support the growth of mould, mildew, fungus or bacteria. The filter material also is resistant to degradation over time and is able to withstand extreme temperature and humidity. Even with all these advantages, the MicroGard filter is still priced competitively.