Otis Technology, AP Brushes, 3 Piece Set, (2) Nylon and (1) Blue Nylon Brush WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov. 2-Nylon All Purpose Brush 1-Blue Nylon All Purpose Brush Made in USA Product Description Double ends allow for large surface scrubbing on one end and precision cleaning with the smaller end. The nylon brushes are the least aggressive, meet Mil Spec and are safe for everyday use. Recommended for use on virtually any surface including wood surfaces. The Blue Nylon Brush features stiff bristles that allow for a more aggressive clean.