his is a pack of two optional Mugen Steel Pillow Ball Adjusting Nuts. Similar to running the Steel Pillow Balls, they will help to improve the steering and handling in bumpy and low traction conditions. The Steel Adjusting Nuts can be used by themselves or with the Steel Pillow Balls as a tuning option. Each part is 3.5 grams heavier than the stock parts.

 https://www.youtube.com/watch?v=1ROiEP_YOJQ