Don't know any details, but for awhile they were "the thing" in locking hubs.
I'm not sure how they relate to the Selectro brand, but both had external knobs. Not sure if one company bought out the other (even MileMarker bought Selectro eventually I think?), or if one simply faded away, or what. At one point they were even part of Bestop I believe. Or maybe they always were?
I'm sure some of the "old" guys will know though.
Hah! Got myself outta that group for a moment!
Paul