Product Description Item's color might be different from the picture because of the aberration.DC-DC adjustable step-down power supply module Input Voltage:5-35V Output Voltage:Continuously adjustable from 1.25 V to 30V Rated Output Current:3A Max.Output Current:4A (more than 15Wpreferably with a heat sink) Adjustment:Apply to 5-35V power sourceuse multimeter to test the oputput voltage and then adjust the potentiometer turn clockwise to step up and counterclockwise to step down Constant current indicator(red) Charging indicator(red) Charged full(green) High-power LED constant current drive Lithium battery charger(including ferroelectric) 4V6V12V14V24V battery charger Nickel cadmiumnickel metal hydride battery pack charger Solar panels and wind turbines Size(L x W x H):Approx:4.8 x 2.4 x 1.3cm