4 Ports USB Hub is multifunctional, which combines mouse pad, calculator and USB hub in one unit. Its Calculator displays 10 Digits, easy to read screen display and big numbers. Calculator is powered by 1 x LR44 button cell, with ON/OFF switch for easy operation. Built-in 4 USB ports can be connected with other computer accessories, such as keyboard, mouse, USB flash, MP3, etc. Set the ON/OFF switch to "OFF" position to turn off the calculator, and then the unit is used as a mouse pad. http://www.chinabuye.com/multifunctional-4-ports-usb-hub-mouse-pad-calculator-with-blue-light