1、Interference Resistance: The relay module has an optocoupler isolation component with high interference resistance. There are also Bluetooth status indicator and relay indicator. 2、Two Interfaces: The relay module retains a UART debugging interface with a baud rate of 9600 and an MCU program interface, which lays the base for your subsequent settings and operations. 3、Current Drainage Protection: This 4 channel relay can be continuously closed 100,000 times, with diode current drainage protection and short response time. 4、Remote Control: Our relay module has Bluetooth module and supports SPP protocol, the control distance can be up to 30M in open environment. 5、Practical and Safe: This relay module is made of PCB material, exquisite craftsmanship, safe and practical, no harm to users, and can be used for a long time. Item Type: 4 Channel Bluetooth Relay Module Material: PCB Control Distance: 30M (open environment) Protection Characteristics: Epoxy resin Contact Load: Low power consumption 1 x Relay Module Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.