Feature: USB Fan Air Conditioner Strong winds and weak wind adjust freely Stepless Speed Regulation Fan Speed Regulation principle: The non-adjustable fan is a 5V direct fan motor,while the two-stall fan is the interior has a step-up circuit board,when placed in the second gear,the boost plate will be USB 5V up after the motor,the air volume is big! The stepless speed governor output voltage range of 2.5V to 8.0V between the smooth change,the amount of free air flow set!and a wider range!Clockwise twist knob can increase the air volume,counterclockwise twist will reduce the air volume,and knob with switch function! Specifications: Power supply Range:DC 4~12V Output Range:DC 2.5~ 8.0V Rated Power:5W (Please do not overload use) Suitable for the very common 5.0V USB fan on the market How to use: Governor male Insert mobile phone charger,charge treasure, computer USB,fan Plug and then insert the Governor head can!Or use the Micro USB 5.0V power supply. Attention matters For two-shift fan,please place the fan in one gear,or you may not be able to adjust speed! Note: Please allow 1-3mm error due to manual measurement.pls make sure you do not mind before you bid. Due to the difference between different monitors,the picture may not reflect the actual color of the item.Thank you! Package Includes: 1x USB Fan Speed Controller