I've had this card a few days now and I can't figure out what the heck it is. The blue connector seems to be a standard floppy interface and fits into a floppy drive. I haven't tried it with a powered on II, though. I remember reading a FD controller can be burned out with the wrong drive attached, so yeah, a bit nervous about it.
All googling brings up useless links. Since I know very little about Apple II hardware (or how to work it) I thought it might be best to ask around here. Electrocution isn't on my agenda. : )
Some of the markings on card - Chatsworth data corporation (card itself), 1APA2.42 (on the large chip), sn7400n (a smaller chip nearby).