Honestly its all BS and over priced
All it is is L Argine which is an amino acid usually found in sexual enhancement blends
If you took 4g of Arginine before your workout you will get great pumps, and its a 1/3 of the cost of NO2,
all it does is oxygenate the blood, and that increases curculation, which in turm dialates the blood vessells as it increases oxygenation, which will make you appear more vascular through out, your workout!
NOW BEWARE, if you have the herpes complex, when you take Arginine, make sure you supplement Lysine