This is a junk item. It's a set of 2, one each from Logicool and Logitech. They were replaced and left unused due to issues such as chattering and unresponsive buttons. As shown in the image of the underside, I disassembled and attempted to clean them once. I believe there are no missing internal parts, but since I disassembled them as an amateur, there may be some scratches or other damage. There is some dirt that couldn't be removed. I'm looking for buyers who can use them for parts, etc. I do not smoke, and I do not have any pets. [Product Details] - Brand: Logitech, Logicool - Model: Trackball Mouse - Model Number: M570 - Accessories: USB receiver - Color: Black Shipping method is [Mercari Delivery]. I will ship promptly after confirmation. Immediate purchase is possible.