Ready to fill. Pre-diluted 50/50. Formulated for stringent corrosion protection. Do not add water. Contains bitterguard to aid in the prevention of swallowing. Shellzone Antifreeze/Coolant pre-diluted 50/50 is a 50/50 mixture of Shellzone Antifreeze/Coolant (concentrate) and deionized water. This low silicate, ready to fill ethylene glycol based product contains inhibitors required to prevent rust and corrosion of all cooling system metals including aluminum. SCA compatible, pre-diluted 50/50 with water, protects against rust and corrosion. ASTM D3306, ASTM D4985. Contains bitterguard, a bittering agent to aid in the prevention of swallowing. Made in USA.