Boiler Rust Inhibitor is a highly concentrated liquid buffered Nitrite/ Borate/ Silicate inhibitor designed for closed loop or open loop Woodstoves or Wood Boilers with minimal water losses. It is: Designed to work most makes and models of outdoor wood furnaces, woodstoves, and commercial and residential boilers. Formulated to provide proper corrosion protection for copper, mild steel, stainless steel and aluminum. It may be used with either hard or soft water and is compatible with glycol anti-freeze. 1/2 Gallon will treat 250 gallons of make-up water. Contains a P Indicator for ease of proper dosage detection (turns your water a light pink). Safe for yearly storage if stored in cool, dark area. $1,000,000 product quality insurance quality! ISO manufactured! Just add directly to your system. Product meets all D.O.T. shipping regulations.