If you're looking for a USB Wifi adapter that will just be used to connect you to the internet, look elsewhere, you'll be able to find similar quality at a lower price. If you're a pentester, read on:

I have half-a-dozen+ monitor-mode capable USB Wi-Fi adapters that I've purchased for various reasons, however I keep coming back to this one. The fact is, the Ralink RT5572 chipset contained in this adapter has some of the most consistently great support among all linux distributions, and is less likely to stop working upon an OS update. I used to think that the RTL8812AU was the GOAT, but currently, their drivers for modern kernels are only available from very specific open-source maintainers (who will also tell you that Ralink is superior). I highly recommend this adapter, even over most Alfa adapters, which I never thought I'd hear my self say. The only way this adapter can be improved is by adding on after-market directional antennas. I use the Alfa APA-M25 antenna, if you have the means, buying two of them would make it even better.

I have tried to install this 5 times on my Windows 8.1 and I get nothing. All I get after installing it is IEEE802.11 WLAN Not exist. I click on Launch Config Utility (after right clicking on their icon), and once again I get absolutely nothing.

Since I know it's not a Plug and Play on Windows 8.1, I don't plug it into the computer until the drivers and utilities are fully installed (of course after nothing has happened once they're installed). I only bought this thing because I can't get 5G from my Netgear Nighthawk AC1750 Smart Dual Band Wi-Fi Router because of my Windows 8.1 and someone suggested this.

Edit:

I just found out my Kaspersky Antivirus is apparently the problem. Unfortunately one of the best antiviruses in the world trumps a $23 adapter. I went without the 5G for this long, it's not going to kill me to be without it. I'm sure this adapter works fine, but beware if you have Kaspersky. I'm too uneasy about completely uninstalling my antivirus just to see if this adapter does work. Even if it does work, does it stop working once I re-install Kaspersky? I'm not about to find out, thank you very much.

I'm changing from 1 star to 4 stars based on Panda's help in this matter.

For Linux users. I bought this adapter instead of a standard adapter because we have a very large old house with 12" walls, and I have trouble with wireless range on most usb adapters. I have been pleasantly surprised by the performance of the adapter, but I have actually been amazed with the performance of the Panda support team. I have been in touch with them several times because I initially had trouble with my 5GHz band performance. They reply at once, and the information they request is cogent and the solutions that they offer are sensible and they work.

The adapter is plug and play for Linux. You do need to install the proper firmware for your distribution, but that is true of any adapter that you purchase. The installation disk only has Fedora files, so you will have to find the firmware necessary for your distribution. For Debian Jessie, for instance, it is firmware-ralink, and for Debian Stretch it is firmware-misc-nonfree. In any event, after you install the proper firmware, the adapter is plug and play. It is also worth mentioning here that if you run PCLinuxOS, the firmware will already be in place and the adapter is truly plug and play. Just configure your internet connection and away you go.

Performance. Ironically, the reason that I initially contacted Panda support is because I was having trouble with stability on the 5GHz channel. I had no such problems with the adapters that I was using, so I was confused that this one would be less effective. It turns out that the extended range of the adapter also meant that interference from a neighbor's connection caused the occasional signal drop. Alex from Panda's support team picked up the problem immediately, and I have had no trouble since.

I can absolutely recommend this adapter for Linux installations.

RLF

This works well on a laptop still running an old centos 7 distribution, so I appreciate the compatibility. It's only glitch is a physical one. If my hand bumps the USB connector to the laptop even lightly, the device disconnects for a few moments. The trick is to avoid doing that.

Excellent range, and the fact that it worked with my Linux (Mint) box without extra drivers -- awesome.

It also works with my Linux OpenSUSE Tumbleweed. Honestly, it probably works with all Linuxii and all Mac and Windows. It's just basically plug-and-play: Ideal.

I must admit I get a glance here or there when at coffee shops (looks a little geeky), but once or twice I've heard comments as people nearby talk, and they've actually been complimentary. I think people are envious! I mean, who hasn't had wifi problems?

Also, I love that it is dual-band: Sometimes my local coffee shop gets a bit of traffic congestion on the normal 2.4GHz (b/g/b) band when there are too many people in the shop.. But the 5GHz band is always open, and probably only myself and at max 2 or 3 others using it. Mua hahahah!!! ;-)

This thing has also been a lifesaver, since the built-in wifi radio on my HP laptop (a RealTek Semiconductor RTL8723DE) does not (yet) have reliably Linux kernel driver support. I just pack this in my laptop bag. And, though not necessary, I do use the extension USB wire (instead of plugging directly into laptop), since it looks less geeky, and I can kind of slide it off to the side.

Yes, I have seen that similar-looking models are available for maybe $10-15 less on Amazon. But I went with the little extra money because this manufacturer is obviously a cut above and takes extra care in a few ways: A) They actually make a box with their name on it B) They go out of their way to advertise that it works with Linux and without need for extra drivers (quite rare, as we know), C) the comments indicate they are reachable for tech support (not just a one-way production line that doesn't want to hear from you).

Thank you, Panda.