Shelly's 120A split-core current transformer scales current values down to standardised units for measurement purposes; an energy monitoring device provides a secondary current proportional to the flow of the primary circuit which can then be measured by an energy monitoring device. ***PLEASE NOTE: The Shelly 120A Current Transformer is not compatible with the Pro EM-50, the Pro 3EM 120A and 400A, the EM Gen3 or the Pro 3EM 3CT63.