This HCG is the original, authentic, Pregnyl, which my doctor has prescribed. I buy it through this site because it is rarely covered by insurance so the cost is about 70% less than purchasing at a local pharmacy. Also, because this product has been written about in the past few years in many, well-known HRT books, such as Suzanne Sommers' best-seller, the product is essential to keep your body's own levels of natural Testosterone production going while on any Androgenic compounds, especially after post-cycle. I definitely notice a difference being on it... Testicles will actually get larger rather than the typical shrinkage.