You can go to the Millennium forum to check out reviews, but suffice it to say this stuff is a REALLY potent endurance enhancer that works great for cardio AND weights. There's a small size too for $10-11 which is WELL worth trying out.
Cordygen VO2 (36 VO2 Caps) By: Millennium Sport Technologies
Cordygen VO2 (36 VO2 Caps) By: Millennium Sport Technologies