Pumps/NO supp.... best form being AAKG (Arginine alphaketoglutarate)
but as mentioned before citruline is used for the same purpose and actually better:
"L-Citrulline is another supplementation option because it is converted into arginine in the kidneys. It also has a better absorption rate. Citrulline is able to increase levels of plasma arginine more effective than arginine itself. For long-term health-related supplementation, L-citrulline may be a better supplementation option than L-arginine."