2 Working Modes:The mobile phone is directly mounted on the WIFl module; the mobile phone and the WIFI module are both mounted on the router Additional Function: Can be used as a USB relay when ESP-01 is unplugged Transmission Distance:When the WIFI module and mobile phone are mounted on the router at the same time, the transmission distance depends on the strength of the router Reserved: UART debugging interface and MCU program download interface 4 Channel Relay Module:4 Channel WiFi Wireless Relay Module Smart Home Phone APP Remote Switch Module ESP8266<br><br>Onboard: High performance microprocessor and ESP-01WIFI module Note: Currently the module only supports for Android system, not for iOS system. The words may be different due to different factory batches, but it not affect the use Color: As shown Material: ABS<br><br>Package Contents: 1 x relay module<br><br>Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.