: This one is credited with the ability to produce stronger and harder erections, increased sexual pleasures, and intense orgasms by promoting blood flow, especially around the erogenous area. The major ingredient is L-Arginine, which aids in the vasodilation of blood vessels. Jelqing is an exercise involving repeatedly pulling the flaccid penis using the thumb and index finger, with the aim of increasing erection size. The idea is that the pulling exercises will increase the blood capacity of the penis' erectile tissue, allegedly resulting in increased length and girth of the penis. Professor Wylie assesses the evidence, effectiveness and safety of different types of penis enlargement products and treatments on the market.