If you're talking about the poly strip showing through the hair, if you have a system that is at least medium density or higher, you are pretty safe. Lighter densities will be more likely to show the poly strip. I wore a poly perimeter for years when I was younger without it being detectable due to the hairstyle(no exposed hairline) and density. A poly strip/perimeter gives a great bond in my opinion using either tape or glue. Clean-up is easy.