The Logitech Trackman Marble USB T-BC21 Mouse is a trackball mouse designed for comfort and precision. With a maximum DPI of 300 and optical tracking method, this mouse allows for smooth and accurate cursor movement. The gray color and sleek design make it a stylish addition to any computer setup. Featuring thumb buttons and wired connectivity via PS/2 or USB, this Logitech Trackman Marble mouse offers a user-friendly experience for those who prefer a trackball over a traditional mouse.