TonLong DC 12V-24V 8A Manual Dimmer Adjustable Brightness for Single Color 3528 5050 Led Light, led strip light There is a black knob, just twirl it to adjust the brightness of LED lights Adjust the light soft and stable, no flickering. PWM digital dimming, avoid rush current, protect your LED lights Size:(L x W x H): about 89 x 60 x 55mm Mainly use to adjust single color LED light lamps and Led Strip.