This is correctly referred to as "Fina"; Finaject is the acetate form of trenbolone. It was produced in a short acting ester (acetate), so its effect lasts only a short time and frequent administration is necessary. Finaject was an injectable steroid of veterinary medicine, which was extremely popular in bodybuilding and powerlifting during the 1980's. Trenbolone Acetate is a steroid having the advantages of undergoing no adverse metabolism, not being affected by aromatase or 5alpha-reductase; of being very potent Class I steroid binding well to the androgen receptor; and having a short half life, probably no more than a day or two though I don't believe this has been measured. Fifty milligrams per day is a good dosing for someone on his first cycle or someone who is as yet less than, say, 20 pounds over his natural limit; while 100 mg/day may be preferred by the more advanced user who has already gained more than this. These doses are assuming that trenbolone is the only Class I steroid being use. There really is no need to stack another -- testosterone being the only sensible exception -- but if another is stacked then the amount of trenbolone may be reduced accordingly.
There used to be a myth that Trenbolone Acetate was "hard on the kidneys", There is a number of users, at doses of 50-100 mg/day, who have experienced no problems. It seems the claims that have been made were from athletes stacking an incredible amount of drugs, and how the blame could have fairly been laid at trenbolone (actually and Parabolan, not trenbolone acetate) is not clear
It is also not clear that Trenbolone Acetate results in any greater degree of increased aggression for a given amount of anabolic effect than testosterone itself does, despite another myth to that effect. The increase in aggressive tendency -- which does not mean the act of aggression -- is moderate and entirely controllable, if noticeable at all.