The Nitrox Pump is made up of several ingredients that have been selected as they have been associated with increased production of nitric oxide in the muscles. Nitric oxide synthases (NOS) are enzymes that convert Arginine and citrulline to nitric oxide. Nitric oxide is a key biological messenger, playing a role in a variety of biological processes. It is known as a vasodilator which enhances blood flow in the body which could in theory increase the delivery of oxygen and nutrients to exercising muscle. This is associated with enhanced muscle pumps during exercise. A low level of nitric oxide is associated with physical fatigue.
Performed on the halfway tumescent penis, jelqing is a manual manipulation of simultaneous squeezing and stroking the shaft from base to corona . Also called "milking",  the technique has ancient Arab origins.  Despite many anecdotal reports of success, medical evidence is absent.  Meanwhile, journalists have dismissed the method as biologically implausible,  or even impossible, albeit unlikely to seriously damage the penis.  Still, if done excessively or harshly, jelqing could conceivably cause ruptures, scarring, disfigurement, and desensitization.