1. Onboard and stable ESP-12F WIFI module, large capacity 4M BYTE FLASH; The I/O port and UART program download port of the WIFI module are all led out to facilitate secondary development; 2. Onboard AC-DC switching power supply module, power supply mode supports AC90-250V/DC7-30V/5v; 3. Onboard WIFI module reset button; ESP-12F supports development tools such as ECLIPSE/for IDE; 4. Onboard 4 5V relays, output switch signal, suitable for controlling the working voltage of AC/Load within 250V/Dc30V; 5. Onboard power indicator, 1 programmable LED and relay indicator. size: 93 x 87mm Material: plastic colour: green Package Contents: 4 x Relay Module 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.