Tube Tests enable the user to easily perform highly sensitive and precise water testing. Using tube tests measurements are considerably faster and easier, particularly in the case of standard and serial tests. Tube tests contain a precisely measured amount of reagent, thereby avoiding the presence of extra chemicals and optimizing test safety. Up to six different measuring ranges are available for the various tests we also provide a full line of COD Reagents. The tubes are made of special optical glass with a 16 mm in diameter. They are supplied in a storage and dispatch box together with the digestion or auxiliary reagents. This packaging unit contains 24 or 25 reaction vials and up to 2 zero vials for photometer system calibration.