BiXPower USB Port Power Cable with 4 Extra Popular Interchangeable Connector Tips This kit comes with a BiXPower USB power cable (USB A male to 4.0 x 1.7mm male); a BiXPower 5.5 x 2.5mm barrel connector ( 5.5 x 2.5mm male with 4.0 x 1.7mm female ); a BiXPower 3.5 x 1.35mm barrel connector (3.5 x 1.35mm male with 4.0 x 1.7mm female ); a BiXPower 2.5 x 0.7mm barrel connector (2.5 x 0.7mm male with 4.0 x 1.7mm female ); a BiXPower 5.5 x 2.1mm barrel connector (5.5 x 2.1mm male with 4.0 x 1.7mm female) The USB DC Power Cable length: 20 Inch ( or 500mm). Its one end is USB A male connector, another end is 4.0 x 1.7mm barrel connector. 4 Extra popular connector tips can plug on USB cable barrel connector to provide different size connectors. Please note that those connector tips are specially designed for BiXPower USB cable and may not fit other cables. BiXNet is the only authorized seller on Amazon to sell this BiXPower USB power cable kit. Caution:Please be advised that the USB cable and connector tips do not have any electronic circuits inside to change electronic voltage/current/polarity. It only provides physical size and shape conversion. A typical USB port output voltage is 5V. When connect the cable to a 5V USB port, its another end with barrel connector will also have 5V output voltage, with positive polarity (inside positive, outside ground/negative). This cable may not be used to power a laptop computer from a power bank USB port. A battery with USB port can only output 5V maximum 10W power. Most laptop computers need 12V or 16V or 19V power. You can not power those laptop computers from a battery with USB port, no matter how big the battery is: wrong voltage.