The SAM-Trackball for PC functions as your regular mouse device and switch interface. Simply plug it into where your current mouse is, and plug your switch(es) into SAM. A switch plugged into one of the switch inputs acts as the corresponding button function (click, double-click) or with Big keys as a key-stroke. It comes with both PS/2 connections and a USB connector. Measures 8"L x 6 1/2"W x 3"H. Latex free. Compatible with Big Keys Keyboard.