Concentrated formula. Contains 100% propylene glycol with inhibitors & protectants. Inhibits fouling corrosion & prevents algae growth while helping in lubrication of pumps & valves. Non-injurious to copper brass & all types plastic except acetate. Protects to -100F. Blended as concentrate non-toxic may be diluted with water according to freeze protection chart provided on bottle label to best suit winter climate needs. Use in all types of water systems: potable solar boiler & boat engines.