Untested. Looks clean. The Vintage Kensington Expert Mouse Version 4.0 Trackball Base is a retro PC accessory that allows users to navigate their computer with a trackball for a unique and nostalgic experience. With the iconic Kensington brand and trackball design, this product is perfect for those who appreciate vintage technology and want to explore a different way of interacting with their computer. This base unit allows users to connect their trackball to their computer for a fun and functional workspace addition.