SONOFF SPM-4Relay Smart Stackable Power Meter The SONOFF smart stackable metering system realizes smart management with overload protection, metadata monitoring and electricity statistics It supports up to 128 channels (up to 32 SPM-4Relay modules), a maximum current of 20A per channel, allows monitoring of 180 days of electricity consumption data, and management of each channel individually The SPM-Main control panel allows 8Gb-32Gb SD memory card for secure local data storage It is a high-performance professional smart home tool for managing homes, office buildings, industrial buildings or even shopping centres, enabling energy consumption monitoring for residents or tenantsNote: module requires SPM-Main control panel, which is sold separatelyFeatures: The SPM-Main communicates with the cloud through Ethernet or WiFi using EWeLink app (Android, iOS), and communicates with the SPM-4Relays through RS-485, which allows for multi-terminal and stable long-distance data transmissionRemote on/off – you can switch all channels on and off remotely anytime, anywhereSynchronisation status – check the actual status of the relay (on or off) using the appDIN rail mounted, like the control panel, to fit the electrical cabinetWith on/off buttonsHousing material made of flame-retardant V0 PC plasticProtection for all channels against overload, overvoltage, overcurrentSpecifications: Compatible with: Sonoff SPM-MainVoltage: 100V~240V ACFrequency: 50/60HzCurrent: max 80A (20A per channel)Number of channels: 4MCU: GD32FDimensions: 250 x 90 x 665 mmHousing material: PC V0 (flame-retardant)Mounting: on DIN railConnectionl: RS485Operating temperature: -10°C~+40°COperating humidity: 5%-95% (non-condensing)Weight: 584gColour: whiteCertification: CE/UKCA/FCC/ROHSWarranty: 24 months