I know about the following (open source ones I think):
* u2fzero
* solo keys
* nitrokey
* tomu + the right firmware (which I guess is not really cryptographically secure)
I'd lean towards the solo keys since it's open source, and I haven't seen any criticisms, but tomu is quite cheaper. Also, which one support “cloning keys” at the setup phase so as to have a backup of your key?
What are your experiences? Recommendations?
