Length Of Hair In Inches: 1- 9/16". MACK 189L Series Grey Squirrel Lettering Quills are still handmade in France & Germany by highly specialized brush makers. The Grey Squirrel Quill is an essential brush for the sign painter. The series 189L is a universal lettering brush. The grey hair has more snap than the brown. It is used for general commercial work such as signs, truck lettering, boats, etc. The grey hair is more durable than the brown, and better suited than Brown Squirrel for rougher surfaces such as stucco and brick.