Each one of these has been said, USB switcher, Screen switcher, and foot pedals. I have this combined, a USB + DisplayPort switcher, with a food pedal to change between the two connected laptops. It's great when it works, which it did in my previous HDMI+1080p screen setup. But as I moved to 4K, I had these issues:

- The noname HDMI cables I had was not the right version, bought 3 new ones.

- The old Apple dongle doesn't support 60hz, luckily I had a newer one which did, worked well on my newer Macbook Pro, but..

- ..Macbook Pro 2016 doesn't support 60hz through the dongles with HDMI, so I've got to move to DisplayPort.

- Now my NEW Macbook Pro doesn't work at all with DP. Macbook issue, as my other 3 Macbooks (on the same macOS) works fine.

So now I am using the KVM switcher for everything except the screen, which I have to manually change the input for, until I can reinstall macOS to see if that solves it (I have spent hours with Apple support).

Overall if you use multiple laptops the KVM is awesome, and the foot pedal is doubly so!