My Japanese Bug
I found this Japanese Semi-Auto Key at the Dayton Hamfest 2005. Some preliminary Google-ing seems to indicate that they mere manufactured by the High Mound (sometimes by an earlier name) company and were distributed here in the 1950's and 60's under several names. Lafayette Radio, Monarch, Radio Shack, and Skillman. This key has a bakelite base and operates and adjusts much like the Vibroplex bugs that I am familiar with. The clear plastic dust cover also quiets the mechanism a little but I find that a full headset works best ;-)
Adjustments require a small open-end wrench. The mechanism has a very crisp and solid feel, albeit noisy. Speed is about 20wpm and up without adding extra weight. Others have added a second weight or a Vibroplex weight to tame them a bit. After some practice and adjusting to the single paddle without a knob (ala Vibroplex) I find it a very nice key that can produce good CW.
Here are some links to other sights with pictures and info: