Mount bracket nut. Rear. A solid metal or plastic block with a threaded hole in the center which is used to tighten or adjust the Stone Guard. Bumper Cover Reinforcement Nut. Bumper Cover Support Rail Nut. Bumper Cover Support Rail Screw. Cargo Net Nut. Mud Flap Nut. Nut to secure Bumper Cover. Included with: Support Bracket.