Nylon is an excellent tip to glass cleaning material, and when the fibers are laid down on the glass, they glide across the surface easily. This dual trim brush splits the best of both worlds by allowing the window cleaning professional to lay the longer outer edges of the brush against glass, allowing the brush to move freely and easily, while the inner monofilament bristles remain in a vertical position allowing the friction from the tips to scrub away caked on dirt and grime. The splay of the outer bristles also allows the bristle tips to scrub into the corners and trim of the window.