This Instrument Can Be Used To Monitor The Coolant Temperature. It Enables You To Quickly Determine When The Engine Fuels Have Reached Their Operating Temperature. The 553 Series' Increased Performance And Accuracy Is Achieved By Its Original Equipment-Type Electric Aircore Meter Movement Or Solid Brass Mechanical Bourdon Tube Meter Movement. All Feature Back-Lit™ Illumination And Include Easy-To-Read Mounting Instructions.