The penis has three chambers of so-called spongy tissue. These will absorb the blood during sexual stimulation, the penis then has its circulatory system that works at full speed. The three chambers are full of blood, and that concludes in the end by an erection of the penis.
When the exercises are done correctly and regularly, then the size of these rooms will expand greatly. This expansion will stay in time. And the penis will be able to accommodate more blood. The penis will mechanically increase its size. The purpose of these exercises is to counter the resistance of the tissues during the swelling of the sexual part of the body by stretching these three chambers. Of course, the manual exercise program should not be too extreme to avoid unnecessary injuries. The traction applied will progressively allow the growth of the tissues and consequently the overall increase of the penis.