* Dietary Supplement * High-Efficiency Magnesium Complex * Maintains Muscle & Nerve Function Ultra-Mag is made with a balanced blend of sources shown to have high bioavailability and absorption. Magnesium is an essential mineral, necessary for producing and storing energy (ATP), allowing muscles to relax, activating over 300 key metabolic enzymes, controlling calcium levels in bones and teeth, and regulating electrical activity in nerve cells.