1PC 450nm engraving Laser Module. 20W, 30W, and 40W are all electrical power! The red and black wires are used for connecting to 12V or 24V power sources, with the red wire connected to the positive pole of the power source and the black wire connected to the negative pole; The yellow and white wires are used to connect 0-5V PWM or TTL signals, with the yellow wire connected to the positive pole of the signal and the white wire connected to the negative pole of the signal.
eBay