The Sonoff SPM-4Relay Smart Switch, in combination with the SPM Main Module (sold separately), enables the measurement of power consumption. It can manage four independent channels and offers the option of using overload protection to protect your devices from damage. The product is also very easy to install - it can simply be mounted on a guide rail. Sonoff SPM-4 relay switches prove useful in many applications. For example, you can use it to check the monthly electricity consumption of your tenants and the energy consumption of a shopping centre or office. The product is also useful in a cryptocurrency mine or server room. Thanks to the overload protection function, you reduce the risk of damage to your devices. How does it all work? Sonoff offers you the option of connecting your devices. The SPM Main Switch communicates with the cloud via Ethernet or Wi-Fi connectivity. This allows the SPM-4Relay switches to be controlled via RS-485, ensuring stable data transmission over long distances. Don't be afraid of connection problems. Would you like to be able to control the power consumption in every room in the office? Or perhaps you want to check how much electricity your tenants are using? The Sonoff SPM-Main and SPM-4Relay switches make it possible. The devices allow you to accurately measure energy consumption and conveniently access information via the eWeLink application. You no longer need to leave the house to check electricity consumption - just pick up your phone.