ZMA is a potent combination of zinc, magnesium, and vitamin B6 that has been shown to increase muscle strength, size, and recovery when used in conjunction with intense weight training. Optimum Nutrition’s ZMA may help you sleep better too, both thanks to its blend of active ingredients and because of the peace of mind you gain from knowing that ON uses only SNAC System, Inc. ZMA, the zinc-magnesium formula supported by published research. Quality Counts: GMP Certified ProductsOptimum Nutrition’s commitment to quality is evident throughout the entire product development process. As a continued measure of quality, all vendors must provide a Certificate of Analysis for each raw material supplied. The certified analyses are also verified through random in-house and independent laboratory testing. To further diminish any chance of physical, chemical, and microbiological contaminants, ON has established and implemented a Hazard Analysis Critical Control Point (HACCP) program. Quality assurance professionals make routine checks on all storage, blending, and production areas and conduct daily inspections.