I just received an email from Bill O'Hara VP of sales, Dexter Marine division in which he stated that they have re-designed the caps to a thicker material (still plastic).
I think a set of polished aluminum caps would be super nice! Consider me very interested.
The ones that came on my '21 Z19 are dexter P/N 81143. They say Dexter Vortex on the face and also what would appear to be a part number 21-281.
Its my understanding that the ones with the big letter "V" on them have a different thread pitch.