PR26 Additive controls cylinder liner cavitation at the same time that it is protecting the cooling system from deposits corrosion. Preparol 26 is designed to reduce inhibitor over concentration and silica gel formulation, all the while protecting any standard coolant system components. PR-26 additive was specially formulated to return the recycled coolant byproduct back to it's original state (after being mixed with water). It infuses corrosion inhibitors and protects internal components of the coolant system, including solder, aluminum, and other metal components within the system. Also will not harm plastics and hoses or other non metallic components. Preparol 26 also restores proper alkalinity and helps prevent overheating and prevents build-up. You will typically use one gallong for everyy 25 gallon batch of recycled end product. Sold in case of 4 one gallon jugs. Plan to use one gallon for every 25 gallon batch recycled. Comes with case of four gallons.