Inner rocker nut. Left. Right. A solid metal or plastic block with a threaded hole in the center which is used to tighten or adjust the B Pillar Reinforcement. A solid metal or plastic block with a threaded hole in the center which is used to tighten or adjust the Rocker Panel. Panel. Body B - Reinforcement. Center REINFORCED plate. Floor Pan. Inner. Included with: Center Pillar Reinforcement assembly, Rocker Reinforcement assembly.