It is a brush set including 12 pieces of nylon brushes, 12 pieces of steel brushes, 12 pieces of brass brushes, 1 piece suitable 1/4" handle and 150mm extension. Brushes are suitable for pneumatic and electrical drilling machines. Can be used on cleaning and deburring the cylinders, bushings, pipes, etc. All brushes are 1/4" and diameter of Ø 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18 - 19 mm.