Plum Flower Brand combines China's rich tradition of herbal formulas with modern international GMP quality control standards. The products are cooked and extraced as a tea using unsulfured herbs. Formulas are then laboratory tested for heavy metals and microbials. Plum Flower strictly adheres to traditional herbal formula recipes and does not add any hidden substances, preservatives or colors to its products. All Plum Flower formulas are made under internationally-certified GMP or "Good Manufacturing Practices" guidelines.