Hardness Factor (Dr. Lamm)
Dr. Steven Lamm, M.D. is a practicing internist and faculty member at New York University School of Medicine. His book Hardness Factor is based on the view that the penis is the best indicator for man's health.
Dr. Lamm Six-Week Hardness Factor Program is a scientific and evidence based routine aimed to improve erection quality through nutrition, supplements, and exercise.
Following Dr. Lamm program should help you to improve your penis hardness, stamina and sex drive, as well as your overall health.