Manufacturer: Supply Solutions HACH 2415915. Digestion vials is used for the determination of Chemical Oxygen Demand (COD). Part Number 2125915, 2125815, 2125925 and 2125825: Vials are US EPA approved for wastewater analysis using USEPA1 Reactor Digestion Method2. Low Range (LR) and High Range (HR) vials are approved by the USEPA for NPDES