Gestodene, also known as 17α-ethynyl-18-methyl-19-nor-δ 15 -testosterone , as well as 17α-ethynyl-18-methylestra-4,15-dien-17β-ol-3-one or 13β-ethyl-18,19-dinor-17α-pregna-4,15-dien-20-yn-17β-ol-3-one , is a synthetic estrane steroid and a derivative of testosterone .   It is more specifically a derivative of norethisterone (17α-ethynyl-19-nortestosterone) and is a member of the gonane (18-methylestrane) subgroup of the 19-nortestosterone family of progestins.  Gestodene is almost identical to levonorgestrel in terms of chemical structure , differing only in having an additional double bond between the C15 and C16 positions, and for this reason is also known as δ 15 -norgestrel or as 15-dehydronorgestrel .  
The original brand name of oxandrolone was Anavar, which was marketed in the United States and the Netherlands .   This product was eventually discontinued and replaced in the United States with a new product named Oxandrin, which is the sole remaining brand name for oxandrolone in the United States.   Oxandrolone has also been sold under the brand names Antitriol ( Spain ), Anatrophill ( France ), Lipidex ( Brazil ), Lonavar ( Argentina , Australia , Italy ), Protivar, and Vasorome ( Japan ) among others.     Additional brand names exist for products that are manufactured for the steroid black market. 
Given YK11’s ability to significantly increase Follistatin production, along with its relatively weak activity at the androgen receptor, it’s likely that its myotrophic effects are mediated primarily through myostatin inhibition. If so, this would make YK11 a solid addition to just about any PED program, aside from those which already incorporate myostatin inhibitors. In my opinion, YK11 is one of the most interesting compounds to hit the market in recent years, but at this point most bodybuilders appear to be unaware, or at least unconcerned with its existence. I expect that to change in the days ahead, as we continue to learn more about it.