Need to identify an old Zinsco breaker
That is an old Zinsco breaker model called &quot;Magnetrip&quot; and there's more than one style. Yours has a forked bus which requires screw terminals top and bottom.
You will not find these new but there are companies who salvage old breakers and load test them and certify them. You will need to source replacements that way.
Still, there is some risk. You really should strongly consider replacing the panel, there will come a day when you can't get replacements at all.
P.S.- there is usually a (safety related) reason when breakers and panels are discontinued...