Default volume control function, clockwise to reduce the volume, counterclockwise to increase the volume, the knob to mute. Compatible with a variety of system devices, suitable for mobile phones, tablets, , desktop computers, compatible with Windoens and Andriod systems. Type-C interface, plug and play. RGB lighting effect, can be turned off. The software can customize the button function: with the key value editing software, different button functions can be customized. Instructions for use: Insert the USB cable, the RGB light turns on, the knob for 2 seconds to turn off the light, and the knob for 2 seconds to turn on the light. Default volume control function, clockwise to reduce the volume, counterclockwise to increase the volume, to mute. Colour:Black Material:Acrylic + Aluminum Alloy Package Contents: 3 x USB Volume Controller 3 x Type-C Cable 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.