Totaltest tube chemical crystals react with acid or moisture when it is present in the system, changing color for an easy visual check|A quick, convenient and reliable way to check for the presence of moisture or acid in refrigerant|Using the Totaltest instrument with the appropriate blue or yellow tube will provide an easy visual test if contaminant exists|Acid test for R-11, R-12, R-500, R-502, R-22, R407C, R410A, R134A|Moisture test for R-11, R-12, R-500, R-502, R-22 The "Yellow Tube" tests for moisture in R410A