GNC Potassium & Magnesium Aspartate: 240-Day Supply Helps Regulate Water Balance. Necessary For Normal Muscle Cell Contraction. Potassium Is Involved In The Regulation Of Cellular Water Balance. Magnesium Is Involved In Nerve, Skeletal Muscle, Heart, And Cell Function. Features 20Mg Of Magnesium Per Serving Supplies 57Mg Of Potassium Per Serving Gluten Free | GNC Potassium & Magnesium Aspartate 250Mg - 240 Capsules (240 Servings)