IRWIN Unibit #21 - 1/2-Inch Shank

Step drill #21: 13/16-inch to 1-3/8-inch capacity, 10 size options. Shank type: 3-Flat, 1/2-inch diameter, prevents slipping in drill chuck. Cutting edge: Single-flute design, ensures true round hole in thin materials. Material compatibility: Ideal for drilling holes in metal, plastic, and laminates. Hole enlarging: Suitable for 13/16-inch to 1-3/8-inch diameter holes in thin materials