Connected to a USB adapter (output current 2A), the voltage can be adjusted with the knob. ☆LED: Green Input voltage: DC5v Output voltage: DC0.6v〜25.8v Please consider the voltage display as a guideline, and use it by measuring the rotation speed with a smartphone app, etc. High voltage break-in of the copper brush is also possible, but when adjusting the voltage, connect the motor at a low voltage, and then turn the knob by hand. Although it is new and unused, it has been powered on for operational checks. The alligator clips are soldered to minimize problems during use. This is not recommended for those seeking perfection, those who are nervous, or those who are concerned. Please confirm the operation after the product arrives and then provide a receipt evaluation. We will not respond to inquiries about defects, etc. after the receipt evaluation.