Siemens 243-0018 SIGNAL SELECTOR, HIGHEST PRESSURE, PNEUMATIC, DA, DUAL INPUT, SINGLE OUTPUTSiemens 243 0018 Signal Selector, Highest Pressure, Pneumatic, DA, Dual Input, Single Output This 243 Highest Pressure Signal Selector is a dual input, single output logic device used in pneumatic control systems to compare pressure signals. It selects the highest of two input signals, is compact and lightweight, and has an operating ambient temperature of 40 degrees Fahrenheit, 140 degrees Fahrenheit maximum. Includes a mounting bracket.