It's similar to Human Chorionic Gonadotropin (HCG), the LH acts on the Leydig cells to produce test, FSH acts on Sertoli cells to stimulate spermatogenesis... It's a better choice if you want to increase the sperm count fast post cycle, or if you want to maintain spermatogenesis during the cycle... Like Human Chorionic Gonadotropin (HCG), it doesn't stimulate gonadotropin secretion, it just substitutes your own LH/FSH and reverts/prevents testicular atrophy...