It may make more sense to read it as Chloride (from Sodium Chloride & Potassium Chloride) = 397 mg.The ingredient list breaks down the number of milligrams of each of the individual elements separately. For Reviver Electrolytes we use both Sodium Chloride and Potassium Chloride, and together that's three (3) separate elements all of which the total milligram amount is listed in the supplement facts.