They use your standard Chinese cherry clone switches. Better than the rubber dome keyboards everyone gets by default, but nothing like a genuine model M. (the other reply linked to a model F which is likely better than the M but I wasn’t aware of that option until now so I’ll have to try it)
Thanks, I was aware of the model F project but didn’t realize they had anything other than very large layout options. I have 4 original model M’s, (two are broken), but my desk is too small with my work and personal computers. (I tried a keyboard switch, but I gave up using it after typing to the wrong computer one too many times)