The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ),  nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone).  Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone .  Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine.  Boldenone undecylenate and trenbolone acetate are used in veterinary medicine . 
What makes Ecdy-Bolin so potent is the natural compound Ecdysterone discovered in the former Soviet Union. What an incredible compound! Not only does ecdysterone facilitate a tremendous amount of positive effects in the body, but it elicits nearly zero negatives! One study conducted by top Russian researchers paired ecdysterone directly against Dianabol, one of the most powerful anabolic steroids developed. The study showed equivalent anabolic activity with one exception: ecdysterone stimulated both slow and the all-important fast twitch muscle fibers, while Dianabol only stimulated the slow fibers! Think about it. Here we have a compound that has gone head-to-head with steroids in studies and won anabolicly with none of the associated side effects of steroids!