Designed for interior and exterior use and made from the highest quality materials, the Albino can stand up to anything you throw at it, and the fully synthetic bristles can withstand harsh chemicals! Set in a durable plastic ferrule, the bristles are both sturdy and soft enough to be used on any surface. NOTE: Sizing refers to the width of the ferrule. Some brushes have numbers printed on the side, for internal designation. These numbers represent half the width of the ferrule.