Logi cool Logitech MX ERGO Trackball Mouse This is a junk item. It's still barely usable, but the left-click sensitivity has decreased, and sometimes it doesn't respond smoothly when clicked. Therefore, I'm selling it as a junk item. Please purchase this item if you understand the condition or are able to repair it. In addition, the area where your hand rests has become whitish due to use, and there is some deterioration. Please purchase only if you agree to the above conditions.