I got one of these (white) in the mail today for the SMK caps lock switch. For the rest of the board, a spring closes a capacitive connection, and around the spring is a rubber dome for cushioning. It feels really really bad.
The "switches" are mounted on plastic, but behind that is a nice curved backplate. I wonder why they even bothered.
Edit: Maybe it's the dome that closes it. Here's a picture. Anyway, it feels super awful, and I think SMK's version (serial number begins with S) is the good one.