Heptapeptide derived from ACTH(4-10). Neuroprotective and pro-cognitive via BDNF upregulation, monoamine modulation, and TrkB receptor upregulation. The ancestral version: N-Acetylsemax is strictly better (more stable, longer half-life, better sustained effects). HOnestly quite overhyped by the loud majority of surface level Nootropics people.
N-Acetylsemax is the preferred form, longer half-life, more stable. Use this if sourcing is easier.