The Electra Check Digital Monitor from TRC is a compact, simple-to-use tool designed with advanced microelectronics which produces accurate testing and analyzing of all AC power sources. Its small size and durable construction lets you easily install this device in an electrical outlet or be used as portable. The RMS voltage and frequency readings are perfect for watching modified sine waves such solid-state generators, inverters and Uninterruptible Power Supply (UPS) products. The Digital Monitor display will change between line voltage in RMS volts and line frequency in Hertz. The LED backlit LCD display has 3 display modes accessible: Alternating Voltage and Frequency, Voltage Only and Frequency Only. Both Voltage and frequency are always displayed no matter what the display mode is in. The Electra Check also features a multi-tone alarm, hands- free auto reset, one button operation, surge protection and wiring diagnostics. Trust TRC, The world leader in electrical safety products for RV applications.