The comparator consists of two wheels with nine color filters, ranging from water white through deep amber, imbedded in each wheel. Simply place a tube of the sample liquid into a slot between the two wheels and rotate the wheels until the color filters are closest in color to the sample. The identifier (Gardner Color Number) of the color filter becomes the description for the sample.

Note: Model 59874-72 has no illuminator and must be held up to a light source.