GO ESTER-C® HIGH STRENGTH + BIOFLAVONOIDS is a high strength, superior Vitamin C formula containing Ester-C®, an innovative form of Vitamin C which provides up to 24-hour immune support. Ester-C® is better retained in the body than standard Vitamin C, allowing it to work longer in the body. Ester-C® is non-acidic, making it stomach friendly and more tolerable at higher intakes than standard Vitamin C. GO Ester-C® High Strength + Bioflavonoids can help you meet your daily needs of Vitamin C.