Hammer-drill bit 3-flat Secure-Grip™ drills faster and lasts longer than others on the market. The 3-flat Secure-Grip shank fits in all 1/2 inch three-jaw hammer-drill chucks and maintains unyielding bit hold with heavy torsional loads. Designed especially for conical anchor, concrete screw, nail-in and hollow wall anchor applications, the bit provides superior performance through its reinforced flute geometry and carbide tip design. offers a complete range of 3-flat Secure-Grip hammer-drill bits in diameters from 1/8 to 1 inch with lengths up to 18 inch.