I purchased a version of the Tuopuke 0-28V Hand Crank Generator. The one I purchased had no bells and whistles and was rated at 15V, 0-3 Amps at 120RPM. The 120 RPM is what sold me. Quite often people pay no attention to the amount of cranking you have to do to reach the advertised Voltage and/or amperage. Mine was waterproof and had the militarry type connector and did not have the voltage regulator package either. This is a rare earth Magnet device, it’s gears inside are Metal and the crank is plated Brass. I tested it at 60 RPM and got my 15VDC @ 1.77 Amps which is not quite 3 amps, but I was not cranking it at 120 RPM either. I am sure if I cranked it at 120 RPM I would have reached the 3 amp rating. The 15 V version I purchased is perfect for charging any 12 VDC Battery Pack. It is superbly built and does what it says it will do. I only paid $38.88 for mine. WHAT A BARGAIN!!!!!!!