USB power cable USB to DC 5.5*2.1mmCharging line power supply line round hole 9V12V boost line USB line [Introduction]: Power the other equipment through the charging treasure. Such as: router, USB light, USB fan, small LCD TV, car purifier, 5V mini speaker, etc... [DC power plug size]: Outer diameter: 5.5mm, inner diameter: 2.1mm; inside and outside negative, line length 1m [The difference between the two lines]9V boost line: with boost components, the USB input 5V voltage through the components, boosted to 9V voltage 1A 12V boost line: with boost components, the USB input 5V voltage through the components, boosted to 12V voltage 1A Purchase according to the following standards 1: Voltage selection Can be directly in the product back label, or the power supply of the product can be seen, there are power input 5V, 9V and 12V standards, according to your router to choose our corresponding boost line.(9V, 12V boost line output 1A, if you are more than 1A, you can't use it) 2: Power plug size specifications If you are not sure, you can consult the manufacturer of the equipment, or consult the merchant who sells the equipment online: whether the size of the power DC plug is 5.5* outside diameter 2.1mm, if you are please choose. Most routers that can be directly outside are 5.5* inside diameter 2.1 You can choose: 1 x DC 5V TO 9V1 x DC 5V TO 12V