Fernox Protector F1 is a market-leading inhibitor which prevents corrosion and limescale formation in central heating systems. Protects against corrosion and scale in mixed metal central heating systems to prevent breakdown and premature boiler failure. When used in conjunction with Cleaner F3 gas savings of up to 15% can be achieved every time you heat your room. Stops frequent venting of radiators and prevents cold spots. One 500ml recyclable bottle treats up to 130 litres of system water (16 radiators) and the equivalent of 250m2 of underfloor systems. Supports boiler manufacturer's warranty requirements. High performance, non-toxic, environmentally friendly - NSF, KIWA and Belgaqua approved formulation