Description: This is a device used to simulate an electrical load, usually for testing purposes. This discharge tester is used for testing a battery or power bank. It can also be used to test current of a USB cable so you could judge if the cable is of good quality. It is designed with a aluminum heat sink and a cooling fan for better heat dissipation, which will start working automatically when temperature is higher than 55C and stops when temperature is under 45. Features: There are 2 adjustment knobs, one coarse knob and one fine knob, that can be used for quick and accurate current control. The input USB port is reversible for easy plug in which mean that you don't have to worry about up or down position of it. Designed with a high standard aluminum heat sink in the middle for better heat dissipation. The cooling fan of 2900rpm will start working when temperature is higher than 55C and stops when temperature is under 45. These is a small LCD display that you can check voltage, current and capacity. Specifications: Voltage Range: 4-30V DC Test Current: 0.1-4.5A Operation Temperature: -10 to 65C Size: 105 x 55 x 43mm / 4.13 x 2.16 x 1.69" Heat Sink Size: 40 x 40 x 10mm / 1.57 x 1.57 x 0.39" Constant Discharge Current: 0.1-4.5A adjustable(coarse adjustment knob for 0-3A, fine adjustment knob for +/-0.2A) Current Error: Less than 2%+3mA Constant Rated Discharge Rate: 35W(if voltage is 21V, constant discharge current should be less than 1.6A) Package Includes: 1 x Load