General description The 4 Channel WiFi Wireless Relay Module is designed for smart home applications, allowing remote control via a mobile phone app. It features two working modes: direct connection to the WiFi module or connection through a router. This versatile module can also function as a USB relay when the ESP-01 is unplugged. Technical specifications Channels: 4 Microprocessor: High performance WiFi Module: ESP-01 Material: ABS Transmission Distance: Dependent on router strength Measurement Error: +/- 1-3 cm Compatibility and accessories Compatible with Android systems only (not for iOS) Package Contents: 1 x relay module Other information Reserved interfaces: UART debugging interface and MCU program download interface Note: Light reflection and different displays may cause color variations in the product image.