Fernox Antifreeze Protector Alphi-11 is a combined glycol antifreeze and inhibitor. Offering long-term protection against frost, internal corrosion and limescale in heating and chilled water systems, including geothermal systems. Compatible with all metals and materials commonly used in hydronic systems including aluminum, Antifreeze Protector Alphi-11, is proven to work efficiently and has been tried and tested on installations worldwide and NSF HT1 approved.