From the Manufacturer:
Source Naturals Nopal Endurance contains
Tex-OE, a patented standardized extract from the prickly pear or nopal cactus that helps support endurance and stamina by priming the body for athletic activity and physical exertion. Preliminary evidence suggests that Tex-OE may support the accelerated formation of Heat Shock proteins (HSPs), stress recovery proteins synthesized by the body to endure physiological extremes. Source Naturals NOPAL ENDURANCE is a critical step towards achieving your maximum potential.