You are correct. They are a switch and a breaker in on. If the breaker pops, the switch flips the other direction.
The main advantage of using them is that you don't have to run a wire to a dedicated breaker or fuse.
Here is a picture of my sub-panels. The row in the top of the picture is mostly breaker/switches and the lower panel is breakers, with the exception of the right most breaker/switch.
In the upper panel, you can see the buss bar which feeds power to the breaker/switches.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html