You need the calipers, the mounting brackets and matching rotors to make the dual piston brakes work. Most Autoparts stores don't include the brackets with their remanufactured calipers based on what I've seen over the years and finding just the brackets after isn't easy.
bought mine with brackets from mitsu graveyard. Advice: don't buy the brakes from them unless you have access to a torch. I had to bring the calipers into auto school to heat them up so the damn caliper slides would come out. But, I got them on and they work great now!
The red piece is the bracket. It bolts to the knuckle and the caliper attaches to it via the guide and lock pins. It's different from the bracket used on the single piston calipers.
