Our N.O.³ Bulgarian Tribulus + OptiNOS Testosterone Booster features Tribulus imported from Bulgaria, this Tribulus is the most bio-active and testable form on the market! Most other Tribulus, which are of Chinese or Indian origin, only test at 4-5% Furostanols. Bulgarian Tribulus 60% Extract clinically and reliably tests at 60% Furostanol Saponins (calculated as protodioscin). This Tribulus is the foundation of our Test Booster product, however we have several other key ingredients