1.Support 3-wire, 4-wire motor stepless speed control, suitable for a variety of server fans and cooling equipment 2.PWM pulse width modulation technology, accurate control of speed, smooth and quiet operation 3.DC 12V power supply design, with independent switch, easy to use. 4. Energy efficient, reduce power consumption and extend fan life. 5. Compact structure design, easy to install, suitable for a variety of chassis and server environment. Parameter: Operating voltage: DC 9-23V (recommended DC12V) Rotation speed (duty cycle): adjustable range 0-100% Warm tips: 1. Wiring requires three lines, positive and negative poles and speed lines; general server fan 8 lines, 2 positive, 2 negative, 2 speed lines, 2 speed lines, connected to the first 6 can be, speed does not need to be connected. 2. Suitable for a variety of server fans, does not support two-line fan. 3. Wiring must confirm the positive and negative poles and then wired, the product does not have reverse protection, reverse must burn! Color: Black Material: plastic Nut color is random, Not accepting specified Package Contents: 2 x PWM Server Fan Speed Controller 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.