OnlyKey Duo - The Best Protection for All of Your USB-C and USB-A Devices

EDIT:After just over a year, I'm changing my review as the product has broken with what I consider to be normal use. This key is far too tight in USB A ports, making it very clunky to use, and the loop is not adequately strong enough to deal with the repeated strain of pulling the key out which has lead to its breakage. For the price, I really hoped for a few more years of use out of this product.Also, its firmware has not seen a single update in two years; longer than I have owned the device. Not only does this suggest the product is now stagnant, this is generally concerning for a security-oriented product. There are competitors which have undergone security audits and release frequent updates. I therefore wouldn't even recommend the full sized OnlyKey unless it receives consistently active development.ORIGINAL:I'll start with a disclaimer; I'm a software developer. This device is exactly what I was looking for and provides a lot of control, but it could be overwhelming for less technical users. There are more simple products which still provide very good security.With that out of the way, this device is amazing. It has the usual hardware key functionality (FIDO2/U2F/WebAuthn) which gives very secure authentication with a single tap. Unfortunately, many websites don't support these standards and TOTP (Google Authenticator) is more popular. That's okay, because you can register a slot on this key to type the six digits, much like it can with a password!It has 6 slots per profile with 4 profiles, so 24 slots in total. Each slot can store a URL, username, password and a 2FA key.All of that and it's secured by a pin which you can put into the device itself, which will protect you from keyloggers. If you're not worried about that, you can type the pin into the app too.For the nerds, this key has its own support for SSH and GPG keys. I prefer to use the U2F functionality in the newer version of SSH, but both work well.A few things you should know:- TOTP only works if you're running the app (also available as a web app) because the key needs to know the time. Not a big deal, just something to be aware of.- The minimum pin length is 7 digits. This is probably reasonable on the original OnlyKey, but it's fiddly on this one. If your dexterity isn't great, you'll have a bad time. You can put it in on the app instead, but the original OnlyKey and an OTG adapter might be better suited to you.- There's no mobile app. You can use the web app, but this only provides the time to the device (for TOTP) and message/file encryption.Even with those caveats, I'm really happy. I don't think there's another hardware key which ticks the same boxes as this one.

Love the idea of the Duo. I have two regular OnlyKey's so I know how they work and think they are very useful.I wanted to leave this in the laptop most of the time and have something a bit easier to store and carry.Like another reviewer stated though, it's such a TIGHT fit. I don't know the USB specs and don't have a caliper on hand, but I'd bet my laptop that the DUO is not within the USB specs. I plugged it into my Asus Zenbook, and another system and I'm surprised it hasn't damaged the ports. It's incredibly tight to remove and I can definitely see it breaking like the other reviewer as I cant remove it by hand. I have to attach the keyring adapter on it to pull it out.Works with the supplied USB-C adapter but that totally defeats my use case of having it left in the laptop most of the time.I'll be returning it sadly. Great concept. Not great in reality.