Amazing product, it has solved my problems.

I have two computers and two monitors connected to both PCs, and through the input, I can use whichever monitor I want on any PC. BUT I had to have 2 keyboards and 2 mice, and I didn't want that. With this switch, I can have up to 4 USB devices for 4 computers. I have connected the keyboard, the mouse, and the USB microphone.

It has a button that you press to switch between computers. It has two lights that turn green or red:
1st light green = 1st PC
2nd light green = 2nd PC
1st light red = 3rd PC
2nd light red = 4th PC

Negatives:
I would have liked it to have audio input and output (microphone/speakers) but fortunately, I solved this with the microphone I have, which is USB and has its own audio output. It is the USB HyperX QuadCast which, since it is USB, can also be transferred from PC to PC with the USB switch, and since it has an audio output, I connected the speakers there. I wouldn't mind if the switch also had audio input/output for audio devices that are not USB.

It was purchased for permanent use with 2 desktops and occasionally adding a laptop. Initially, as shown in the photo, it has 4 ports, so it can share up to 4 devices (e.g. keyboard, mouse, camera, external hard drive). What is not immediately apparent is that it distributes them to up to 4 devices. In other words, it can be connected to 4 different PCs and controlled with the same peripherals through it.

As a sturdy device, it doesn't seem flimsy. Control is done through separate buttons with a 2m cable, so it can be placed wherever each person finds convenient for immediate switching.

A mouse and keyboard with LED and macro commands are connected to it without any problems. Each cable is quite long, about 1.5 - 2m each. The switching is immediate and there is an LED indicator for which PC it is controlling.

When transferring files from a USB stick, it performs at normal levels of a USB 2.0 controller, so don't expect high speeds in this aspect.

It also has a mini USB port for extra power supply if the connected devices are power-hungry.

In conclusion, we are talking about a device that delivers on its promises without adapters and complicated connections. In terms of quality, it justifies its cost.

CAUTION: IT IS ONLY A KVM FOR USB PORTS. IT DOES NOT WORK FOR MONITOR CONTROL!!!!

I needed it specifically now during the lockdown with remote work, in order to use the same keyboard and mouse for both my work laptop and my home desktop PC, whether I have them both open at the same time or if I close the laptop when work hours are over and switch to my desktop afterwards, without having to connect the cables one by one.

Note:
Since KVM switches that support not only keyboard-mouse switching but also display (especially modern ones with DisplayPort or HDMI) are hard to find and expensive, I found a simple solution to have display switching: since both my monitor and my graphics card have multiple ports (both DP and HDMI), I made sure to connect the monitor to both PCs simultaneously, so the monitor automatically turns on when I first open one PC, and when both PCs are on, I switch the image source from my monitor's control panel.

MAIN ADVANTAGES:
- This specific model (US424) has 4 classic USB 2.0 Type-A ports (not Type-B, which are common in other switches and require adapters for keyboard or mouse), so you can redirect 2 additional devices, from USB sticks and external hard drives to printers. Moreover, it has a minimal price difference compared to the corresponding model with only 2 USB ports (US224).
- The switching is immediate and seamless, with the press of a button (which, as shown in the second photo I uploaded, is separate, with a long and thin cable, so you can have it accessible wherever it suits you). The main device has 2 lights that alternate, depending on the connected PC (and they even have green or red lights, depending on whether the PC is on and sending power or not).
- The length of the cables is just right for you to have the main device at the edge and only the button near you. There is no issue with which PC you have directed your devices to and if the PC is on at that time, with one or two presses, within 2 seconds at most, the mouse/keyboard will be activated on the desired PC. So even if you place the main device with the lights out of sight, it doesn't matter.
- Power cable is not provided because it is not needed. However, if someone connects 4 USB devices that consume a lot of power and do not have their own power supply, the ATEN has a mini DC IN 5V port in the front to cover you.
- Overall, I consider ATEN a very reliable company, based on user reviews and what I observe when visiting their website.