PowerMate by Griffin is a USB-powered device that spins like a knob and clicks like a mouse. It can be used to control the volume of your PC or Mac, scroll through documents and even to create music and edit movies just like the pros. The highly precise wheel makes editing easy in any application -- simply assign any command you would like it to execute. For Mac users, the PowerMate comes preset to work with iMovie and GarageBand, right out of the box!