Tungsten Carbide Reinforced Head, Black Oxide Finish Contains the following drills: 3/16" x 4", 1/4" x 4", 5/16" x 4", 3/8" x 4", 1/2" x 4" Plastic re-usable drill index with bits clearly visible. Round shank designed for rotary and percussion hammer drilling. Drills through block, brick, stone, concrete & marble. Induction-hardened body for straightness & strength. Precision-ground tips are carbide grade BC20. Engineered with wide flutes for fast dust removal. 3/8" reduced shank on 1/2" bit