The mechanism that caffeine increases activity by is via antagonizing adenosine A2 A receptors (the standard mechanism of caffeine). Adenosine normally suppresses the effects of dopamine on locomotion (via working in opposition on neuronal excitation  ) in the striatum where A2 A and dopaminergic neurons co-exist, and preventing this suppression with an antagonist increases the effects of dopamine on D2, of which include spontaneous activity and (in rats) rotational behaviour when unilateral lesions are induced in the striatum.   Non-caffeine adenosine antagonists also share this effect on locomotion, further implicating A2A antagonism and dopamine as the cause rather than a separate, unseen effect of caffeine.  As for why A2 A is mentioned more frequently than A1 in this section, it is since A2 A receptors appear to co-exist with dopamine receptors in many parts of the brain (nuclear accumbens, striatum, tuberculum olfactorium) whereas although A1 are heterogeneously expressed in the brain, there is no pattern with dopamine receptors.  Interactions with motor control appear to be highly relevant to the striatum, where A2 A predominates.
Products are first and foremost sterile, they all pin very easily with no noticeable pip, even with the higher dosed test. As far as dosages go, I keep it pretty simple, I stay on year round and run anywhere from about 500-1200mg of test weekly depending on what I'm trying to accomplish or where I'm at with my training. Everything else is pretty much thrown in from time to time. All the products both injectables and orals produced an enhanced state of recovery & strength gain, as well as the expected differences in symptoms/user experience associated with each compound.
It shall be noticed, that in men, approximately 5% of testosterone undergoes 5α-reduction to form the more potent androgen, dihydrotestosterone (DHT), also known as androstanolone. From another side approximately % of testosterone is converted into estradiol (the primary female sex hormone) by aromatase an enzyme expressed in the brain, liver, and adipose tissues. Hence, don`t forget to take precautions to avoid respective side effects. Thereof we recommend to perform blood works and take aromatase inhibitors on cycle (if required, anastrozole preferably) and SERMs (clomifene, toremifene) during post cycle therapy (PCT).