YK-11 is a very powerful SARM, popular with bodybuilders and athletes. It is particularly effective in building lean, high-quality muscle, with no side effects.

Selective androgen receptor modulators, or SARMs, are a new class of androgen receptor ligands.
They have the same effects as androgenic drugs, but are much more selective in their action, enabling them to be put to more uses than the relatively limited legitimate uses of anabolic steroids.