Trust TK-2500P 2in1 Optical Trackball with Integrated Numeric Keypad Trust TK-2500p 2-in-1 4-Button USB Optical Trackball Mouse w/Integrated Numeric Keypad General Features: Black design with purple trackball USB interface (36-inch cable length, approximate) 4 button optical trackball with integrated numeric keypad Ergonomic design with foldable stand at the bottom for best working position