Not for use by individuals under the age of 18 years. Do not use if pregnant or nursing. Consult a physician or licensed qualified healthcare professional before using this product if you have, or have a family history of prostate cancer, prostate enlargement, heart disease, low “good” cholesterol (HDL), or if you are using any other dietary supplement, prescription drug, or over-the-counter drug. Do not exceed recommended serving. Exceeding recommended serving may cause serious adverse health effects. Possible side effects include acne, hair loss, growth on the face (in women), aggressiveness, irritability, and increased levels of estrogen. Keep out of reach of children.
The second theory is similar and is known as "evolutionary neuroandrogenic (ENA) theory of male aggression".   Testosterone and other androgens have evolved to masculinize a brain in order to be competitive even to the point of risking harm to the person and others. By doing so, individuals with masculinized brains as a result of pre-natal and adult life testosterone and androgens enhance their resource acquiring abilities in order to survive, attract and copulate with mates as much as possible.  The masculinization of the brain is not just mediated by testosterone levels at the adult stage, but also testosterone exposure in the womb as a fetus. Higher pre-natal testosterone indicated by a low digit ratio as well as adult testosterone levels increased risk of fouls or aggression among male players in a soccer game.  Studies have also found higher pre-natal testosterone or lower digit ratio to be correlated with higher aggression in males.     
Fit Crew USA offers its flagship product Xtreme Testrone as a free and no obligation trial offer. Upfront, users only have to pay the shipping costs, and the company will dispatch a full-sized bottle of the formula to their home or business address. Pricing for the formula product starts at $ for a 1 month supply. A much better deal is to buy the product for $ for a three month supply. With this package deal, users get the product for an inexpensive $33 per month and bottle. It does not get much cheaper than this for a testosterone boosting proprietary formula like this one.