Sunscreen agent, formerly known as phenylbenzimidazole sulfonic acid. Ensulizole is the established name that must be used on sunscreen labels (Source: www.fda.gov). It is primarily a UVB-protecting sunscreen agent, providing only minimal UVA protection. Ensulizole protects the skin from wavelengths of UV light in the range 290 to 340 nanometers, whereas the UVA range is 320 to 400 nanometers (Source: United States Pharmacopeia (USP), http://www.uspdqi.org/pubs/monographs/sunscreen_agents.pdf). For complete protection, this ingredient (as well as many other UVB-protecting sunscreen ingredients) must be paired with the UVA-protecting ingredients avobenzone (also called Parsol 1789 and butyl methoxydibenzoylmethane), titanium dioxide, zinc oxide, or Mexoryl SX; outside the United States it can also be paired with Tinosorb. Because ensulizole is water-soluble, it has the unique characteristic of feeling lighter on skin. As such, it is often used in sunscreen lotions or moisturizers whose aesthetic goal is a non-greasy finish (Source: www.emedicine.com/derm/topic510.htm).