Use Thermo Scientific Orion AQUAfast Digestion Tubes, Reaction Tubes and Liquid Reagents with Orion AQUAfast colorimeters and Thermo Scientific Orion AquaMate Vis and UV-Vis spectrophotometers. Digestion and reaction tubes contain the precise amount of reagent, are made of special optical glass and fit the Orion™ AQUAfast COD165 thermoreactor.