You might recognize this interesting new component from behind-the-scenes studio clips of audio recording equipment or even music videos. A fader is a control device for fading or changing the sound volume, light intensity, or simply the gain on an audio or video signal.
Here is a small, black handheld-size DIY version for your next audio or music (maybe even with a NeoTrellis?) project. Connect the red wire to 5V, black wire to ground, and the yellow wire to your input to get a smooth-to-operate control with a pro quality feel. This isn't a potentiometer, instead it uses a hall effect sensor: this means no scratchy, jumpy or worn out knobs after years of use.