This is a vintage Compaq MO42KC Mouse Scroll Wired Ball in Black is a classic piece of computer hardware that offers a simple yet functional design. It uses mechanical tracking method and has 3 buttons. The scroll wheel adds a convenient feature for scrolling through long documents or websites. This is an OEM unit from Compaq. It’s as brand-new as possible with no scratches or imperfections. It works perfectly and is sturdy accessory for any vintage computer setup.