We test all strains for heavy metals, biological contaminants and alkaloid content. Each sample size is grouped together by color and then tested on an aggregate basis. Since each color is tested as an aggregate, the alkaloid content values may vary slightly from one sub-strain to another. For example, for whites we carry White Thai and White Maeng Da. If the respective mitragyna values are 1.5 and 1.6 – the aggregate value in total for ‘white’ is 1.55. This helps keep prices down while still being 100% thorough.