Phenibut is an amino acid related to GABA, used as an ingredient in dietary supplement products.
The included 5cc scope (1 teaspoon) for Phenibut measures out 4000mg, please only use 1/4 of the scoop (1/4 of a teaspoon) which measures out 1000mg, to measure 500mg, it would be 1/8 of a scoop, an amount which can vary up or down by up to 20% depending on how level the scoop is and how densely packed it is. A scale is recommended for handling and accurately measuring pure ingredients.
It is highly recommended by most independent sources that Phenibut not be consumed more than 2 days per week; more frequent Phenibut use will reduce the benefits.
It is highly recommended by most independent sources that the amount of Phenibut consumed at once should not exceed 1000 mg, and the amount of Phenibut consumed in one day should not exceed 2000 mg.
More information about Phenibut can be found at wikipaedia/phenibut