I disagree with the previous responses. After reading in detail how it works and how your workout must be altered to gain results from it... I had the idea to try it in conjunction with NO2. Since NO2 is a hemodialator, I figured it would help the circulation of the Endothil into the bloodstream to better affect the muscles being exhausted.
The highest free weight amount I had ever benched before, was 175lbs. After only one month of using the NO2/Endothil combo, my free weight bench max was 200lbs (I did 5 reps). And that was without ever using a spotter. Its been 2yrs since then and I haven't worked out since, unfortunately, but my size gain has remained. I actually just received a shipment today of NO2 & Endothil to give it a go for another month. Personally, I believe it does work and will keep using it. NO2 & Endothil combined really works great!