Sustanon 250 is a potent combination of four esters; testosterone propionate, testosterone phenylpropionate, testosterone decanoate and testosterone isocaproate. All four esters have different half lives; propionate has a half life of one day, phenyl propionate has a half life of 1 to 2 days, the half life of isocaproate is 4 to 5 days and that of decanoate is 7 to 8 days. The esters having short half life release quickly in the body but wear off quickly too thereby needing frequent doses. The esters with a long half cycle stay in the body for long but take time to become active. The different half cycles make Sustanon 250 quite useful and the users require just one dose per week. This is one of the reasons users buy Sustanon 250.