Thank you for viewing. I am selling this item as I no longer need it, having used it for about two months. There is no instruction manual, but the connection method is described on the box. VGA PC Switch RS-230U A switcher that can switch between 2 PCs via VGA, supporting a maximum resolution of 1920x1080. - Model: RS-230U - Connection method: VGA, USB - Number of supported PCs: 2 - Supported OS: Windows 11/10, Mac OS X 10.5 or later - Function: Switching keyboard, mouse, and monitor - Output resolution: Maximum 1920x1080