It may be a GFI breaker. Without pictures we can only guess.
Richard & Jill
2014 Flagstaff 832IKBS Classic Super Lite
2018 Silverado 1500 Crew Cab Z71 4WD All Star Edition
Camping since 1989
Car Shredder Op/Tech, Scrap Metal Recycling - retired
Everyone gets confused at some time, some are better at hiding it than others.
The disadvantage of the factory configuration is that the converter does not have a separate circuit breaker. It's usually combined with the fridge AC on a single breaker since the 2 combined are less than 700 watts. Combining the fridge and converter on the same breaker means a problem with one device takes out the other. I felt (and feel) that was an unnecessary risk with an extra AC breaker slot readily available.
Since I was replacing the WFCO/Converter panel (8735P) with a Progressive Dynamics equivalent (4135), I bought 2 half width breakers (combined in one package) to replace the single wide breaker. This gave me an extra breaker to move the converter to. A 10 amp breaker each for fridge and converter is more than sufficient, although wiring will support 15A. 15A breakers are more commonly available, but HD had both sizes in the right format.
2019 Flagstaff T21TBHW A-Frame (same as Rockwood A213HW)
2008 Hyundai Entourage minivan
camping Colorado and adjacent states one weekend at a time