I recall seeing them in early '80s, looks like you have the questionable finned Scott Mathauser pads, too. These have a reputation for danger because it's been said the the friction pad, glued on to the alloy holder, can come unglued when you least want that to happen. But there's little/no documentation of it actually ocurring. They took 'em off the market, so it may have been true or just the market's fear and lawyers having their say. You don't see these calipers often, wonder if they are collectable to somebody...