All QRS spirometers use pre-calibrated, disposable mouthpieces. educe the liability from cross-contamination and eliminate the need for sterilization. These mouthpieces are individually calibrated during production using the same equipment LDS Hospital uses to validate spirometers against the American Thoracic Societys Recommendations for the Standardization of Spirometry. These pneumotachs are single patient use only. Box of 100.