Parabolan is trenbolone cyclohexylmethylcarbonate. The half-life of a steroid ester is mostly dependent on its ratio of fat solubility to water solubility: the longer chain the ester, the higher this ratio, and the longer the half-life. This particular carbonate could be most closely compared with an enanthate ester; the half-life is probably a little less than week.
An amp (76 mg trenbolone cyclohexylmethylcarbonate) of Parabolan is comparable only to 58 mg of trenbolone acetate. (The acetate is a little more potent, more effective per milligram, because the acetate ester is lighter and therefore a higher percentage of the weight is trenbolone.)