Black button. Generally used for hard to reach areas in paint, rust, and weld removal. Handy quick change tool for disc grinding which fits any standard 1/4 in drill or air tool. Abrasive Backing Type: Cloth, Abrasive Backing Weight: YF Weight, Abrasive Mineral Type: Aluminum Oxide, ANSI Grade: 24, Color: Green, Diameter: 3 Inch Primary Trademark Name: Green Corps