The Electra Check Digital Monitor is a compact, easy to use instrument made with advanced microelectronics which provides accurate testing and monitoring of ALL AC power sources. Its small size and rugged construction allows for convenient installation in an electrical outlet or use as a portable tool. The RMS voltage and frequency readings are ideal for monitoring modified sine waves such a solid-state generators, inverters and Uninterruptible Power Supply (UPS) products. The Digital Monitor display will alternate between line voltage in RMS volts and line frequency in Hertz. The LED backlit LCD display has 3 display modes available: Alternating Voltage and Frequency, Voltage Only and Frequency Only. Both Voltage and frequency are constantly displayed regardless of the display mode. In addition to these features, the Digital monitor also features a multi-tone alarm, hands- free auto reset, one button operation, surge protection and wiring diagnostics.