You dont know what to choose K0ntakt and the most important information at the bottom expand About the seller SINGLEPHASE ACTIVE AND APPEARANT POWER METER, AMMMETER 100A 300VAC RMS, DIN RAIL Universal meter of electrical quantities (also effective, e.g. active power ) . The device can be powered from the mains or devices generating sinusoidal voltage with a frequency of 4565Hz, connection to an accidental inverter may damage it Behind the meter (between it and the device to be measured), converters (power regulators, inverters etc.) can be used. Builtin functions: wattmeter (0.030000W RMS) voltammeter (0.030000VA) power factor indicator (cosfi 0.01.0) voltmeter (80.0300V AC 4565Hz) ammeter (0.00100A AC RMS) Use the SAMCK button to switch the set of parameters displayed on the lower display: cosfi factor; wattmeter (active power), voltmeter (apparent power) The builtin electromagnetic transformer simplifies the connection (shown in the figure below) to apply voltage to pins 1 and 2 and pull one wire through the hole in the meter. The device shows the active power, i.e. the amount counted by a typical household meter or the apparent power (which must be taken into account in industrial installations). Dimensions 65mm x 80mm x 54mm parameters Uwe: 80300VAC 4565Hz Active power consumed by the 4W meter Accuracy 1% / 2 digits Degree of protection: IP20 Refreshing: 2 times / second The device is calibrated, however, it has no certificates of verification and cannot be used as a main energy meter.