The Logitech Amofferextrous Trackman Marble USB T-BC21 Mouse Trackball is a unique and versatile mouse designed for those who prefer a trackball for their pointing needs. With a maximum DPI of 300, this mouse offers precise and smooth cursor movement. The mouse features a thumb button for added functionality and has an optical tracking method for accurate performance. With connectivity options including PS/2 and USB, the Logitech Trackman Marble is a reliable choice for users who value both comfort and efficiency in their computer use.