I found the answer to my own question..... The crown cap is also called a crown dip and is the 6-7 inch colored dip the arrow makers put on the arrow before fletching and cresting.

I use the vinyl wraps for the same purpose. Onestringer makes some awesome ones.

I prefer white nocks, white fletch with a white barred cock feather and white wraps. I got no trouble following the arrow flight that way and you would be surprised how prevalent white is out in the hills and woods. It actually is a natural color unlike the flourescent colors often used for vanes.