Marine Line includes our innovative Checker HC handheld colorimeter. Hanna Instruments took the technology used in much more expensive portable and benchtop photometers and applied it to handheld colorimeter that allowed the aquarium enthusiest to perform laboratory quality analysis. No more color cubes that are subjective to the color interpretation. The Checker HC is based on the Beer-Lambert Law of absorbance to use a light source and detector to measure the color change. The results are then displayed digitally.