Product Information: Easy to read indicator and designed for the popular modern Ethylene Glycol antifreeze. Suitable for use on OAT (Organic acid technology) antifreeze Number of floating discs measures the level of coolant protection Tests at hot and cold temperatures. Reads in Celsius and Fahrenheit. Floating orange disc shows over protection and loss of efficiency. Bulb is Black, 6 discs. For Propylene Glycol antifreeze use Part No 4292. A 50/50 mixture of antifreeze and water will give full coolant protection and is suitable for most climates.