Model USBSSP helps protect the USB port of your computer against power surges and other voltage disturbances on your USB cables. USB signals have a clamping voltage of 5.1V. The power line has a clamping voltage of 6.8V. Model USBSSP plugs into the host computer or hub. Requires no additional cables or drivers. Dimensions: 4.5 x 1.2 x 1.0 in (11.4 x 3.1 x 2.5 cm).