I wanted some info on a square D breaker I came across. It looked like a Type QO. The only difference in the design was there was hook type connection to the panel. The part of the breaker that connects to the detail of the panel had a normal QO style clip. I didnt get the model # of the breaker..any info would be great...

That hook type arm was usually on a QO tanden (piggyback) breaker. There is a slot it goes in so it will only fit in certain opening in the panel

I think that it is made for older panels. The instructions I thought said that it was used in panels before 1967. Its been a while since I saw it so Im not sure.

The tamdem breakers with the "hook" are the newer style of CTL breakers. As velect said the purpose of the hook is to limit the locations these breakers can be installed.

Curt