Shurhold's special application series of brushes is designed for more specialized work beyond just regular washing. This series includes attachments compatible with Shurhold handles. These are based out of a solid wood block with a rubber wrap-around bumper to prevent marking any surface. This SHUR-LOK attachment that quickly locks into any Shurhold handle features blue nylon bristles designed for working on vertical surfaces and is safe on delicate surfaces like isinglass and Plexiglas.