NP3 Bolt Catch Plunger
Your standard Mil-Spec plunger except coated in NP3 or Nickel Teflon for extreme corrosion resistance and lubricity. Excellent for carbines and rifles that like to get wet, dirty and pushed to the extreme. Kind of like your Ex.
Pic shows NP3 plunger in comparison to the standard mil-spec plunger.