Tribulus 1500 by APS contains an extract of Tribulus terrestris herb (aerial parts – leaves and stems) and contains an unprecedented Bulgarian Tribulus extract that is standardized to contain an unprecedented 90% total steroidal saponins, 60% furastanol saponins, mainly furostanol glycosides (including protodioscin and protogracillin) and small quantities of spirostanol glycosides, sterols and other compounds. Unfortunately, 99% of all products on the US market contain little if any Protodioscin! This is important because Protodioscin is the active constituent in tribulus terrestris that is responsible for stimulating the Luteinizing Hormone and ultimately raising testosterone levels (naturally). Protodioscin is the compound in tribulus proven in Bulgaria and Russia to Increase LH and Testosterone levels. Due to the complicated purifying process to identify the active ingredients it takes 1,000 lbs of raw Tribulus Terrestris to make just 40 lbs of Tribulus 1500!