With NEMA mounted 1 control panel, duplex units are start/stop control with alternation. The Champion R-Series compressors are proven, high quality units, ready to run. The R-Series are unique as they can be customized. Standard Features: -Load-less starting (via centrifugal unloader) for lower energy costs and less wear on drive motor -ASME inter-stage pressure relief valve for protection with pump belt guard. -ODP NEMA 1760 RPM electric motor -10 Micron industrial grade intake filter -ASME coded receiver -0-300 PSIG air pressure gauge on tank Single phase-115/208-230 (Magnetic Starter Included, Alternator on Duplex Units)