Omnadren 250 is an oil-based injectable containing a blend of four different testosterone compounds: testosterone propionate, 30 mg; testosterone phenylpropionate, 60 mg; testosterone isohexanoate, 60 mg; and testosterone hexanoate, 100 mg. Because Omnadren contains four different testosterones, many people will compare it with Sustanon.
Omnadren does contain testosterone propionate and testosterone phenylpropionate in the same strength as Sustanon; however, testosterone isohexanoate and testosterone hexanoate replace the testosterone isocaproate and testosterone decanoate in Sustanon. As a result, Omnadren has a very different effect than Sustanon. To begin with, users of Omnadren will experience a heavy water retention. Unlike Sustanon, Omnadren readily converts to estrogen, which may cause gynecomastia. The estogen-linked side effects can be reduced or prevented with the simultaneous use of Nolvadex (tamoxifen citrate) and Proviron (mesterolone).
Source : www.xtrememuscle.net