The etrailer Electric Trailer Brake Kit item # AKEBRK-35-SA, you were looking at, are the correct replacement brake assemblies for your 2012 Forest River R-Pod 177.
These brakes are 10" x 2-1/4" and are made for 3,500 lbs axles. They are self adjusting and fit 13" to 15" wheels. The E-coated backing plates resist wear and corrosion and have a 4 bolt brake mounting pattern.
I have linked an installation video below. view full answer...