What is the function of the front windshield wiper arm nut cap?

Prevent The Windshield Wiper Arm Nut from Rusting.
The Windshield Wiper Arm Nut Cover Can Effectively Prevent The Nut from Being Exposed to External Moisture, Dirt, and Other Environments, Which Can Prevent The Nut from Rusting and Extend Its Service Life.
The Nut Cover of The Windshield Wiper Arm Can Tightly Fix The Connection between The Wiper Arm and The Windshield, Ensuring That The Wiper Will Not Shake or Shake during Use, Improving The Cleaning Effect.
The Windshield Wiper Arm Nut Cover Can Effectively Prevent Nut Loosening or Friction, Reduce The Possibility of Noise Generated during Wiper Operation, and Provide A Quieter Driving Environment for The Driver.