A "Wooster 2" Solvent-Proof Chip Brush" is a type of brush used to apply coatings, adhesives, or solvents that would destroy normal brushes. "Solvent-proof" means that the bristles and handle of the brush are resistant to solvents, which are often harsh chemicals used in cleaning, painting, and adhesive applications.
The term "chip brush" often refers to a brush with thicker and stiffer natural bristles (commonly made from hog hair), making it suited for applying thicker coatings such as adhesives or harsher paints like primer.
The 2" measurement refers to the brush's width, which indicates how much space it can cover in a single stroke. Wooster is a recognized company that produces high-quality painting equipment.