Chrysin is a naturally occurring extract from the Passiflora coerulea plant.  This substance is another testosterone booster that works in a different manner than DHEA, Androstene, Norandrostene, Androdiol, etc.  This product will minimize the conversion of testosterone to estrogen.  This kind of product is known as an anti-aromatase.  There are several prescription anti-aromatase agents such as Teslac or Cytadren.  This supplements was shown in one study to be nearly as effective as Cytadren.  I am a little skeptical of these claims but there is no doubt that it is significantly minimizing testosterone conversion to estrogen.  Once estrogen levels get to a certain level in your body it signals the pituitary gland to shut down testosterone production.  With a supplement like this your body would continue to produce even more testosterone naturally.  For those that dabble in anabolics that will convert to estrogen it would give you a legal anti-estrogen supplement to battle all of the bad side effects that it causes such as gynocomastia, etc.