Mason Natural Vein Erect with L-Arginine & Maca Capsules contains a concentrated form of maca herb together with the amino acid l-arginine which may help support normal stamina and endurance.Mason Natural Vein Erect with L-Arginine & Maca capsules contains a concentrated form of maca herb together with the amino acid l-arginine which may help support normal stamina and endurance.The herb maca and amino acid l-arginine are known for supporting normal health blood flow. Healthy blood flow is essential in order to boost stamina and endurance. Having these two supplements together in one formula is an easy and convenient way to get these two important nutrients for circulation.Support Wellness: Explore our full catalog of products including collagen, probiotics, melatonin, fish oil, ginkgo biloba, antioxidants, zinc, ginger and calcium.