Designed according to the ohm's law principle, and through the resistor in parallel through another switch, it can produce 3 kinds of resistance of the new USB load discharge resistance, when all the switches open, it is 2.2 ohm/10W, 4.7 ohm/10W, 2 kinds of resistance in parallel At the same time, With 5V voltage, it almost can produce 3A discharge current. Actual current size, please according to ohm's law: I = U/RReistor in parallel calculation formula: R = 1/(1/R1 + 1/R2 +.+ 1/Rn)K1 = 4.7Ohm/10W , K2 = 2.2Ohm/10W The charging device works, the winding resistance caused by the high voltage current, produces a very, very high temperature, therefore in the process of use and just use the finished one in a short time, Absolutely can not human exposure of the gold metal parts for the radiator to avoid burns! Nor to the tester on flammable objects, to avoid fire! In the process of use, he must be very vigilant! Considering the specificity of heat resistance, the initial use of electricity will appear some white smoke and smell after a period of time, because outside the paint, it contains very little moisture, electrically heated at high temperature, moisture evaporates from the white smoke phenomenon, produces a specific smell by using the high temperature of baking paint outside the phenomenon, It completely disappears after using for a period of time. This phenomenon is inevitable, belongs to the normal situation, you don't need to worry about the load tester may be damaged, please rest assured that the use of Loads: It can be convenient to test the power supply of the mobile charging device, mobile phone charger, the USB output current is such as to mark, as long as the USB connection above. And it can do it on mobile power and USB power adapter aging test, aging test discharge resistance will be hot, temperature is controlled in 80 - 85, please pay attention to prevent hot Size: 6.5x2.2cm/2.56x0.87inch Quantity: 1pcNote: Please allow 1-3mm error due to manual measurement. Pls make sure you do not mind before you make a bid, due to the difference between different monitors, the picture may not reflect the actual color of the item. Thank you!Package Contents:1 x USB Tester