Provides long-term protection against corrosion and limescale formation in domestic central heating systems. This inhibitor prevents corrosion and limescale build-up and includes enhanced pH buffering to maintain the system water pH between 6.5 and 8.5, the optimal range for preventing corrosion and limescale. It is compliant with BS 7953:2019 regulations and requires annual concentration checks as part of system servicing for long-term protection. Compatible with all other Fernox products and suitable for all materials and metals used in central heating systems, including aluminium. Protects against corrosion and scale in mixed metal central heating systems. Stops frequent venting of radiators. One 500ml recyclable bottle treats up to 130 litres of system water (16 radiators) and the equivalent of 250m2 of underfloor systems.