Anti-Freeze, Non-Toxic, Propylene Glycol Formula with freeze protection to -100º F. Good with aluminum components...formulated with metal corrosion inhibitors, particulate suspension additives and red color. Ask for the best. Ask for the original Freeze Free. This industrial coolant and heat transfer fluid is the best on the market. Recommended for solar heating systems, home boilers, summer cottages, RVs, boats, trailers, cooling towers and more. Freeze Free will not adversely affect neoprene seals used in hydronic boilers, nor will it damage aluminium boilers. Freeze Free is a red liquid that is practically odorless .