1. Based on the 40-pin GPIO interface, suitable for a series of motherboards. 2. Uses high-quality relays, allowing the connection of loads: AC 250V, 5A or DC 30V, 5A. 3. Equipped with optocoupler isolation to avoid interference from high-voltage circuits. 4. Comes with a relay indicator light for easy viewing of the relay's working status. 5. Comes with a relay jumper cap for easy switching to other pins for control. Product Name: Relay Expansion Board Load: Less than AC 250V, 5A or less than DC 30V, 5A Applicable Models: Suitable for 4B/3B/3B+, Nano Product Size: 65.15×56.21 mm Color: Blue Material: PCB + Metal Package Contents: 1. One 3-channel relay board 2. One pack of screws Only the above items are included in the package, and no other products are included. Note: Light reflection and different monitors may cause slight differences between the color of the item and the actual object. The allowable measurement error is plus or minus 1 - 3 cm.