Our Timed Release Vitamin C provides you with 500 mg of Ascorbic acid per tablet which releases over a prolonged period of time. Vitamin C is essential to many functions in the body and helps fight cell-damaging free radicals.† Antioxidant Support Immune System Support† For additional formula information view the supplement facts panel. All Windmill supplements are manufactured in the United States in an FDA-inspected facility whose cGMP (current Good Manufacturing Practice) are independently verified by qualified certification organizations. Free of artificial colors flavors and preservatives Windmill is a trusted name that has been providing America with quality supplements for over 45 years.