BEVRLink 4.7k Ohm Resistor 2 pcs

The resistors are needed if connect directly between a 3.3V microcontroller / 3.3V single-board computer and the relay.

This product includes 2 pcs 4.7K Ohm Resistors.

Example:

More examples of how to wire between a microcontroller/SBC and the relay

BEVRLink 4 Channel Relay

BEVRLink 8 Channel Relay