HD COOL TEK ULTRA is an anti-corrosion coolant concentrate that builds a protective layer on the inside surfaces of the cooling system (engine blocks, cylinder heads, liners, water pumps and radiators).HD COOL TEK ULTRA must be diluted in water to be used as a coolant.Also available as a 50:50 mix called HD COOL TEK.ADVANTAGES : Optimal protection for all engine metallic parts. High performance additives protecting against freezing, overheating, corrosion and scale. Long lasting anti-corrosion properties on all engine components thanks to the Lobrid Si-OAT technology. Reinforced aluminium protection at high temperature. Eliminates the risk of scaling and deposits in the cooling system. Avoid cavitation and increases water pump lifetime. Compatible with gaskets, hoses, and plastic components. Nitrite free / amine free / phosphate free / borate free.