SONOFF SPM 4 Relay Smart Stackable Power Meter

Connect up to 32 SPM-4Relays】One SPM-Main can be connected 32 SPM-4Relays. Each SPM-4Relay has 4 isolated channels to help you manage devices more conveniently. 【Power metering】You can monitor the power consumption by checking eWeLink App on your mobile phone. Obtaining current, voltage and power easily. 【Max. 20A/Gang】Each channel can support maximum current of 20A, no fear of high power load. 【Communicated by RS-485】The SPM-Main communicates with the SPM-4Relays through RS-485, which allows for multi-terminal and stable long-distance data transmission. 【Overload Protection】Once the overload protection is enabled, it can protect your devices from burning out. Note : The Main Unit and 4-Relay of the Stackable Power Meter need to be used together. The Main Unit is connected to at least one 4-Relay to function.