Sustanon 250 is an oil-based injectable testosterone blend, it typically contains four different testosterone esters: Testosterone propionate (30 mg); testosterone phenylpropionate (60 mg); testosterone isocaproate (60mg); and testosterone decanoate (100 mg), although a lower dosed version is also produced. An intelligently “engineered” testosterone, Sustanon is designed to provide a fast yet extended release of testosterone. The propionate and phenylpropionate esters in this product are quickly utilized, releasing into circulation within the first four days. The remaining esters are much slower to release, staying active in the body for about two and three weeks (respectively). This is a big improvement from standard testosterones such as cypionate or enanthate, which provide a much shorter duration of activity, and a more variable blood level. As with all testosterone products, Sustanon is a strong anabolic with pronounced androgenic activity. It is most commonly used as a bulking drug, providing exceptional gains in strength and muscle mass. Although it does convert to estrogen, as is the nature of testosterone, this injectable is noted as being slightly more tolerable than cypionate or enanthate. Many individuals may likewise find it necessary to use an antiestrogen, in which case a low dosage of Nolvadex (tamoxifen citrate) or Proviron (mesterolone) would be appropriate. Also correlating with estrogen, water retention should be noticeable with Sustanon. This is not desirable when the athlete is looking to maintain a quality look to the physique, so this is certainly not an idea drug for contest preparation.