Type: II (Synthetic Filament), Grade: A (High Grade), Size: 4 (102 mm, 4.00"). Made with natural hog bristle or synthetic filament. Flat, metal bound paint & varnish brushes come in several different grades. Grades AA & A are thicker brushes & feature superior paint loading & release. Grade B is excellent for utility painting. Grade C is suitable where a professional finish is not required & for one time applications such as applying adhesives, cements, etc. Hog bristle brushes should be used only with solvent or oil based coatings. Synthetic fiber brushes may be used with solvent, oil or water based coatings. (Described by Brush Bristle dimensions) A-A-3192