Review on Rybozen KVM Switch HDMI 2 Port Box with USB and HDMI, Share Keyboard Mouse Printer and HD Monitor, Support 4K HUD (3840x2160), includes 2 HDMI and 2 USB Cables by Zach Sornsin

I use the switch because I want to run the Windows desktop and Raspberry Pi 4, mainly to see how the Pi 4 works. I always worry to connect something either because I always know that there will be problems. My monitor didn't have an HDMI port, so I use an HDMI to VGA converter. But this setup worked on the first try. I have a keyboard and mouse that switch between computers and the output monitor is fine. I only use one USB port as I have a wireless mouse and keyboard combo so I don't know how the other ports work or if there is USB in and out. I don't need this now, so I haven't tried it. Bottom line, it works the way I wanted it to, so I'm happy with it.