GMP is the Less Pure version, which is also why it costs less. Your would want 191AA. Of course I'm partial to Viking Nectar (VN) because I was involved in the manufacturing process from the beginning. It consistently tests at 98j.9% pure, it ships from w/in the U.S. so it's far faster to your door, and since shipping is included, it's the cheapest solution. But hey, what do I know? Here's the link if you want to research: https://livelikeaviking.com/viking-nectar/