The base construction of the PAC series is a ceramic substrate, also known as ceramic rod. Metal caps are pressed over the ends of the rod. The resistor element is a resistive wire which is wound in a single layer on a ceramic rod. The ends of the resistive wire and leads are connected to the caps by welding. Tinned copper-clad iron leads with low heat conductivity are employed, permitting the use of relatively short leads to obtain stable mounting without overheating. The resistor is coated with a green silicon cement which is non-flammable, will not drip even at high overloads, and is resistant to cleaning solvents specified as per IEC 60068-2-45.