TESTOSTERONE U 300 (Nebido) – is an extremely large/long ester base testosterone compound that is primarily used in the treatment of low testosterone. Nebido, as a testosterone hormone, like all testosterone hormones carries an anabolic rating of 100 as well as an androgenic rating of 100. This is an estrogenic anabolic steroid in that it does aromatize at a fairly significant rate. As a testosterone compound, Nebido will also carry one of the longest half-lives of any testosterone or anabolic steroid available. Nebido carries an active half-life of approximately three months. Compare this to the more popular Testosterone Cypionate and Testosterone Enanthate, which both carry half-lives a little greater than a week and you can begin to understand how slowly acting Nebido will be.