Known as FernBlock, this is a patented active from Heliocare, developed alongside Harvard medical school. It is derived from a tropical fern native to South America, and works by protecting against UVB-induced sunburn, as well as protecting against UVA and Infrared wavelengths. The active is also able to support cell renewal and protect from cumulative damage caused by sun exposure (such as ageing and DNA damage). It is an antioxidant, protecting against free radicals, and has been shown to boost production of collagen, elastin and hyaluronic acid in the skin.