Compact Keyboard with trackball G84-4400 integrated with 16mm trackball and two mouse button. Individual keys have long service life: approx. 20 million key operations. Interface available in USB or PS2. Extremely flat design and lightweight model. It's perfect for 19 inch applications, Slimline PCs and notebooks. It also has additional input options for pen-based computers. Features Integrated 16mm trackball plus 2 mouse keys Interface : USB or PS2 ML technology with Gold Crosspoint contacts Service life of individual keys > 20 million operations